Yep, I'm assuming that's what Americans get weirded out by. Which is just weird because it's definitely a minority of toilets anyway. The vast majority of toilets in cafes, restaurants, bars, and large shops (or indeed any business where it's normal to be there for more than 10-15 minutes) are either publically accessible and free to use, or can be accessed with permission. It's generally frowned upon to walk into a business, use the toilet, and not buy something though, and even cafes and restaurants will only let you use the toilets if you buy at least one drink, so it could be that Americans are running into that.

There's also a thing that only some businesses have toilets positioned in a place where customers can access them - obviously if it's a tiny shop and the only toilet they have can only be reached by going through the stock room, they're not going to let people just wander in and out (and may also be barred by their insurance policy from letting non-staff into the back rooms.) They might bend that rule for someone they know, but not for someone they don't - in my home town, I know several businesses that would let me use their toilets in a pinch, but they wouldn't let a complete stranger do so (they trust me not to nick stuff, or know where to find me if I do!) So there's definitely a bunch of social conventions about when and where you can use a business's toilets, which I can easily see Americans tripping over. As I understand it, the approach to customer service is quite different in the US compared to here.