It’s not all machines. Some have rotary pumps which are very nice and quiet.

And some have a manually-operated lever, which is completely silent.

The ones out there now are wonderful, but quite huge and expensive because they rely on AC motors which sadly aren't very power dense and don't scale down well

Rotary pumps aren't that big -- most of the premium espresso machines with vibration pumps are actually bigger than the ones with rotary pumps, i.e. compare a dual boiler or heat exchange vibration pump like Synchronika with a Linea Micra or Lelit, with two boilers and rotary pump.

It was this exact question that lead me down the rabbit hole to making espresso machines. The main reason everyone uses them is because they're $25, small, and can leverage the oscillation of mains voltage for their operation. The next best thing is probably $300 and quite large and heavy - and those professional gear pumps fundamentally don't scale down well. Ours operates under the same principle though with a completely different sort of motor that hasn't been common until pretty recently.