Except that you can add new soles to Birkenstocks. People keep them (with resoling) for over 20 years.I bought a pair of Hey Dude 'shoes' (they are really overpriced slippers?) and after wearing them for a few days was struck with the idea they are just Crocks with fabric, and totally not recyclable. I felt some guilt too. But they are comfortable. I will wear them until they aren't wearable again. It doesn't deflect from their lack of recyclability, but will at least delay their replacement. I love Birkinstocks, and wear them until the sole completely disintegrates, after trying to prolong their demise for as long as I can. Yeah, fashion is hard on the environment. Think of trillions of pairs of 'yoga pants' filling landfills...
As to Crocs...they are an abomination. I don't care how 'comfortable' they supposedly are. They're literally made from plastic and are therefore future landfill and ocean and water microplastics. Not to mention they are gross and don't breathe. I don't want to think what someone's feet are like after removing them. Ugh.
If people must wear unmentionably hideous 'shoes', they should at least be made out of natural materials that will degrade rather than persist for decades (centuries?). Leather, cork, rubber, felt, wool...there are so many choices. And continuing to use plastics just fuels the global petrochem industries and all of their lobbying against better and actually beneficial technologies.