Yes but they're the easiest to ramp up and wind down. Certain segments of the economy as devastated right now. Would not want to be a flight attendant, but airplane engine mechanics are probably still in demand as cargo flights replace passenger traffic (since we're ordering everything online now).

Logically, that would extend to people whose job revolves around signing up restaurants to marketing portals. The restaurants that have an online business are already there. Those that don't have an online business are already closed.

According to flight aware, global air traffic is down 75%. So I'd bet mechanics aren't doing so hot either unless they were dedicated to cargo.

Programmers arent as easy to replace because they already understand the system. Training takes time, and if there's not enough documentation then you'll end up contacting the previous programmers for help (I've seen it happen) anyway.

Yes. But now they have no one to call.

Marketing and SDRs are really easy to scale up/down; there are some things that are specific to each product but generally it doesn't matter what you are selling it is the same soft skills. Account Executives and Sales Engineers who provide long term support are a lot harder to replace though.