Different point of view, though maybe an edge case:
As someone with what would be size 15 shoes in the US or larger since my teens, I was used to going through 5 shoe stores to find someone who even had a single pair that was roughly my size.
Forget about models, comfort, colors, prices or any other choice. It was get that single pair of possibly basketball shoes that were closest to my size at whatever prices they were asking.
So I prefer ordering shoes online, because I'm more likely to find shoes in my size because
a) the number of stores I can search in a day is bigger,
b) there might be specialty "big and tall" stores from the other side of the country among them, and
c) if a store does only or a lot of online sales, their customer base is possibly the entire country, so it makes a lot more sense for them to also have a few shoes in less usual sizes in stock compared to a store with only the population of its immediate surrounding area.
So I'll gladly spend 20 minutes sending non-fitting pairs back until I find some that reasonably fit.
Because the alternative for me more often than not will be to waste an entire day running around the city and still returning empty-handed or paying twice the price for that one somewhat fitting pair I found and that I didn't even liked.
Also, since a lot of the stores pay the return postal fees, they're kind of interested in that you keep the shoes.
So some might have more detailed size charts where they tell you how to measure your feet and then tell you what size of which brand should be the best fit for your foot size.