Unless I know something is what I really want, I'll buy it in a store. Clothes are a good example- returning something because it doesn't fit is a hassle (because the shipping is expensive so there is an incentive to make it a hassle), so I don't do it. And so the supposed savings from buying online evaporate. (And of course stores prevent the problem in the first place because you can try it on.) I used to buy a lot of clothes online but now I basically never do. The experience really kinda sucks.
Tee shirts just fit. Polo and casual business wear just fit. Underwear is simple for guys, if the old one fit, the identically spec'd new one will fit (my wife claims that is not the case for women). For about a decade until quality fell thru the floor my default "asphalt hiking athletic shoe" for long distance urban exercise was, per my amazon list of orders, a "New Balance Men MX623 10.5 4E" and they fit like a glove every time. Not even a break-in period believe it or not, off with the old shoe on with the new. Pants just fit. Buddys jeans made in the USA just fit. For footwear if you spend enough money it fits, Thorogood / Weinbrenner products are very expensive and made in Wisconsin and fit perfectly out of the box like a glove; they also last forever. If you have to ask if you can afford them the answer is no, but they last for a decade or two so the annual cost is actually cheaper than buying cheap boots.
I would not attempt a tailored suit over the internet, your local tailor is not likely going to be amused you bought it online when you bring it in for adjustment. My wife can spend a seemingly infinite amount of time trying on different cocktail dresses. Not all stores for all clothes will go out of business. Merely almost all of them.
I'm just calling out that maybe 95% of my clothing was either a gift or purchased online and I've never had the slightest problem. Generally speaking things that involve paying a tailor probably should be purchased directly from a tailor but other than that...
Actually it's quite easy to make clothing to measure if you take proper measurements. My SO makes a lot of specialty outfits for cosplayers and theater shows, and she regularly makes outfits for people she's never measured herself. They usually fit perfectly.
Your local tailor will gladly take these measurements for you. $20 for five minutes of work is easy money. Also, why would a tailor not be amused if you brought them a product and paid them to alter it? Not all alterations are possible of course, but they'll be happy to try. In fact, AFAIK it's common advice that you can get a generic suit from Men's Wearhouse or something and get it tailored up to look nice...
Most tailors are perfectly aware they're competing with mass-produced clothing from Asia. There's some bargains especially if you are only going to wear it once or twice. But in the end you usually get what you pay for, the quality and durability is not as good as from a tailor who did it right.
The other thing is the sizing - a lot of stuff from Asia is sized for tiny Asian people, especially women's clothing is often several sizes smaller than US clothing. But on the other hand sometimes it's department-store clothing that is being sold off-label direct from the factory. I would look at it as largely the same bag in terms of quality. Not every department-store dress is made to last either.
Places like Amazon/Zappos make returns pretty hassle free. But I don't disagree with your basic point. I do buy clothes that I can't buy locally or are a known quantity from someone I order from repeatedly. But, when you're not sure of exactly what you want, no one has really cracked the code for online clothes shopping and, because it's a very tactile experience, it's hard to see how you really get there.
