Terminology
- Checkout friction – anything in the buying process that creates resistance or a reason to give up, whether that's a surprise shipping cost, a forced account creation, or a form that takes too long to fill in on a phone.
- Conversion rate – the percentage of visitors who actually complete a purchase, as opposed to browsing and leaving.
- CAC (Customer Acquisition Cost) – how much you spend on ads or marketing to bring one paying customer to your store.
- Guest checkout – letting someone buy without forcing them to create an account first.
- Accelerated payments – options like Shop Pay, Apple Pay, and Google Pay that let customers complete a purchase in a tap or two without filling in card details every time.
Imagine a restaurant that spends a fortune on glossy ads, social posts, and a beautifully designed menu, gets people through the door, and then hands them a bill with charges nobody mentioned when they ordered. Service charge, table fee, a charge for the bread that arrived without being asked for. Some people pay it quietly. Most don't come back. A few tell their friends. Running paid traffic into a Shopify checkout with unresolved friction works in much the same way, except the bill arrives at the very moment someone's got their card out, and by then the opportunity to smooth it over is already gone.
The frustrating part is that most brands diagnosing a traffic problem are actually sitting on a checkout problem, and those are two very different fixes with very different price tags. Buying more visitors is expensive. Removing a friction point often costs nothing beyond the time it takes someone to actually sit down and look.
Where the ad budget quietly disappears
Baymard Institute's research across 50 studies identifies unexpected extra costs, typically shipping fees and taxes only revealed at the final checkout step, as the single biggest abandonment trigger, cited by nearly half of all shoppers who leave without completing a purchase. That's not a targeting problem or a creative problem. Showing a shipping cost earlier in the journey, on the product page or in the cart rather than at the payment screen, removes the surprise before it does any damage. It's one of the highest return changes available to most stores, and it costs nothing to implement.
Forced account creation is the second most common friction point, with around a quarter of potential customers leaving when they're required to register before purchasing. This one tends to frustrate people disproportionately because they've already decided to buy, and then something entirely unrelated to the product stops them. A guest checkout option resolves it immediately, and most Shopify stores can enable it in settings without touching any code. The fact that a meaningful number of stores still don't have it turned on is, if I'm honest, a bit baffling.
Mobile sharpens all of this considerably. Mobile cart abandonment runs significantly higher than desktop, and mobile now accounts for over 60% of ecommerce traffic, which means a checkout that feels clunky on a small screen isn't a niche problem affecting a handful of visitors, it's the primary experience for the majority of them. Form fields that don't autocomplete properly, payment options buried several scrolls below the fold, order summaries that eat half the screen before the card details even appear, these things feel manageable on a laptop and genuinely obstructive on a phone. The gap between how a store owner tests their checkout and how most customers actually experience it is often wider than anyone realises until they actually try it on their own device.
The thing paid traffic actually does to a broken checkout
More traffic into a checkout with unresolved friction doesn't dilute the problem, it amplifies it. Every additional visitor hitting the same sticking points is another potential sale lost to the same fixable issue, just at higher volume and higher cost per session. Baymard's research draws a useful distinction between natural abandonment, people who were genuinely just browsing with no real intent to buy, and avoidable friction, people who wanted to complete the purchase but hit something that stopped them. Paid traffic, particularly paid social, tends to over-index on the first group because those visitors are being pulled away from something else rather than actively searching. So the channel most brands reach for when they want more sales is also the one most likely to deliver people with the least committed intent, and the least tolerance for a checkout that asks too much of them.
The fixes for most of this aren't complicated, which is part of why it's strange how often they go unaddressed. Show shipping costs before the payment screen. Enable guest checkout if it isn't already on. Make accelerated payment options like Shop Pay or Apple Pay visible and prominent on mobile rather than buried below a long form. These changes don't require an agency, a developer, or a significant budget. They require someone going through the checkout on a phone, as a first-time visitor would, and paying attention to what actually slows things down. Most store owners haven't done this recently, and some have never done it at all, which is understandable given how much else there is to run in a small ecommerce business, but it's also where a significant chunk of otherwise salvageable revenue tends to disappear.
Paid traffic still matters, and there's a point at which fixing the checkout leaves you needing more visitors regardless. But the sequence matters enormously. A checkout converting below what it's capable of means every visitor, paid for or otherwise, is worth less than it should be. Pouring more budget in before addressing that is just paying more for the same leaky outcome.
