This is a benefit to the worker. They’re leaving because they got a better paying gig or less work/fewer hours for the same amount of money.

Yes, because there's no union there to bargain for better pay, bonuses, more time off work, and so forth. Tech is a new industry where workers have more bargaining power on an individual level because expertise is so sought after. Now imagine combining that with unions and we'd probably all be doing 4 day work weeks already, like unions are currently bargaining for in various countries. We'd likely also have more time for tech debt, as unions increase certain types of innovation.

Like, if unions can do this for McDonalds workers after a sympathy strike in Nordic countries:

Every few months, a prominent person or publication points out that McDonalds workers in Denmark receive $22 per hour, 6 weeks of vacation, and sick pay. This compensation comes on top of the general slate of social benefits in Denmark, which includes child allowances, health care, child care, paid leave, retirement, and education through college, among other things.

Why would we assume tech workers in a very profitable industry wouldn't be able to get away with even more?