Some ways in which the ergonomics of most off-the-shelf UK bicycles are (needlessly) worse than a car:

Imagine if, to drive at night, you had to buy some lights and strap them to your car, remembering to take them off individually at each destination in case they got stolen, and recharge the batteries when you got home.

Imagine if, to signal in your car, you had to open the side door, lean out and wave.

Imagine if, when you wanted to carry more than a backpack in your car, you had to buy aftermarket storage accessories and fix them to your car because it didn’t come with any luggage capacity.

Imagine if, to park your car, you had to attach a special parking stand to it.

Imagine if driving in rain and puddles flicked up spray and mud up across your windscreen until you installed aftermarket mudguards and wipers.

Imagine after you’d driven your car in the rain, you had to wipe it down and regularly clean degrease and regrease the gearbox to keep it running smoothly.

Perhaps the biggest ergonomic factor is infrastructure though - imagine your car had to share the road with lorries that could legally travel at a speed of 200mph.

You *can* get some bikes off-the-shelf that come with dynamo lights, panniers, mudguards, kickstands, maybe even sealed gear boxes and belt-drives.
But maybe people only want to buy them if they feel cycling is a reliably safe mode of transport, and not just a form of exercise.

eg, only 2/26 bikes in stock in Halfords (the biggest UK bike retailer?) have racks or mudguards (and they're both folding electric bikes) https://www.halfords.com/cycling/bikes/bikes-available-stock/?start=24&sz=24

even the "commuter bike" section isn't much better https://www.halfords.com/bikes/commuter-bikes/