I'm not going to say they're ubiquitous in the automotive world (assuming non-belt-driven like you mention below), but they're hardly brand new. The battery-electric buses in my city have heat pumps, and (IIRC) other cities opted for air conditioning in their trolley-bus fleet over a decade ago. Built to automotive standards is hardly uncharted waters.

Though perhaps I'm simply blown away living in a colder climate. Resistive heating if it's only to defog windows in the morning, or similarly rarely used, is reasonable. Resistive when getting started (one major hurdle, ICE -> EV, resistive -> heat pump, at a time) is reasonable. I just thought the automotive world had moved forward more rapidly than it had.

I don’t know why they made the choices they did. You will note that I said I was guessing at development.

The evidence is that engineers on greenfield projects at multiple companies on multiple continents all arrived at roughly the same solution.

Make of that what you will.