My personal favorite part is that you don't have to do this mental math of "the frame is this much, then pick lenses you want depending on your budget, etc." The price of the frame is the only thing you pay, all the fancy lenses and such are free, whether you need them or not (in case of sunglasses). With frames being noticeably cheaper than other brands and lenses being free (usually the bulk of the cost of prescription glasses), they are welcome to put their hand in my wallet.
The only reason I don't shop there much anymore is because of LASIK. Back then though, I had about 4 different frames from Warby Parker, and those were my favorites, despite previously wearing the usual "known" eyewear brands (and that's even without factoring in the cost).
P.S. There are some extra charges for lenses in rare scenarios, like if you have a very very strong prescription, they charge you a bit extra if you want to make the lenses thinner. Still not comparable to traditional glass brands though in terms of how much it costs.
P.P.S. There are other affordable online eyewear places, but I have been appalled with the quality and look of those. A couple of friends of mine tried Zenni Optical before, and those frames felt flimsy and they didn't look good at all imo. Warby Parker seems to have found a really solid niche between "cheap and flimsy" and "overpriced brand name eyewear", which is "the quality and looks of premium eyewear, but with a much more reasonable pricing".
I prefer smaller, traditional wire frames because that's what I've always worn (and at this stage in life that's unlikely to change). Unfortunately, wire frames seem to be out of fashion and no-one seems to have a good selection.
Furthermore, I have a fairly strong prescription and with my current frames, the lenses are about 8 mm thick at the edges, and my frames are the smallest I could find. The larger the frame, the thicker the lenses end up being. I could go with a higher-index lens material, but then chromatic aberrations become way too distracting, and I'd rather have a thicker lens than deal with that again.
P.S. Those "rare" scenarios you refer to are not that rare. My mother gets her glasses from WP, and they end up costing several hundred Canadian dollars, about the same as Costco. My mother's prescription is also not that strong or unusual; like most or a lot of old people, she is both near-sighted and far-sighted, and while bifocals might be an option, most people seem to prefer transition lenses (I think that's what they're called).
Wish I could find glasses with ear hooks. They only make them for kids now.
That, along with the other severe distortion brought on by a -10 diopter, is why I mainly wear contacts now.
I still have high-index lenses, but ones with a lower index of refraction and therefore a higher Abbe number. I don't remember specifically which material I have, but I think it might be high index 1.6 (index of refraction) with an Abbe number of 42. Chromatic aberrations are minimal enough with these lenses that they don't bother me much anymore (although still present).
For comparison, crown glass and CR-39 plastic have Abbe numbers of about 58, but will result in much thicker lenses at stronger prescriptions. Regular high index plastic lenses have the some of the worst Abbe numbers, and the higher index you go the worse it gets (Abbe of 32–36), but lenses can get very thin with high index 1.74. More on this at [2].
I've worn contacts several different times, but not only could I not get used to removing them from my eyes, I didn't like how much they worsened my close-up vision, and you can't just take off contacts like you can glasses.
This[1] comment by @mindslight on HN last year was a big help. In the end, I did have to switch providers when Costco didn't have any other material options (I got my glasses from Zehrs Optical in Canada). I payed about $325 altogether, but there was some sort of deal on so I don't know how it would be normally.
[1] https://news.ycombinator.com/item?id=19315769
[2] https://www.2020mag.com/article/does-material-abbe-value-inf...
I found a style of frames I really like and now I just keep buying them in different colors so all my lenses are interchangeable.
At Costco you can try and choose the frame directly and at the end walk away with higher quality glasses for the same price. Same with contact lenses - you can’t buy same brands of contact lenses cheaper even online.
(A theory certainly could be that customer acquisiton was cheaper when Warby Parker was started and there were fewer direct to consumer businesses, it was more novel).
If the difference between companies that succeeded and failed was just "do they have a good product at a good price" there wouldn't be much to write about!