In most hiring settings this isn't true though. Language-specific skills actually do matter, for all but entry-level positions at massive tech companies. It's not like my 3 years of experience in Ruby is immediately translatable to Java/Python/whatever. Could I get up to speed in those languages in due time? Sure. But if you were on a hiring committee, hiring for a team that works mostly with Java (or whatever) would you rather hire me or the version of me that's had the same amount of experience but with Java?
Well they cater to the wealthy. Who else could afford adding 30% to their grocery bill every week? And the wealthy are better equipped to weather a downturn than anyone else.
I think this is better stated as "consumer behavior does not always map to MY logic". Paying for Instacart is a logical decision for some people (or at least they think it's a logical decision). I would never be a customer but that doesn't inherently mean it's a bad business or people that are customers aren't being logical.