Are you implying that their interest suggests that non-shit AR glasses will actually happen in the relatively short term? Big tech companies were and ostensibly are interested in self-driving too, and that seems to be taking much longer than they expected.
They all keep announcing AR features for their devices and operating systems, even though those are very niche except as a "gee isn't that nifty" demo on current hardware—anyone who's held a phone or tablet or Gameboy or whatever up to interact with these things can attest it's pretty terrible overall UX, even if it's really cool as a demo. Glasses fix that problem. I assume the reason companies are continuing development of those capabilities is that they're pretty sure AR glasses aren't too far off. Seems like a much more tractable problem than self-driving, anyway—mostly a waiting game for battery and display/input tech to hit just the right spot and for someone to package it just right, like smartphones were.