True enough bus conductors were thought an unnecessary expense at one time and buses where the driver has to take money and issue tickets brought in.
There were quite definitely no prams on buses in the two cities I knew best as a child and young adult. I have no idea when Glasgow Corporation brought in the possiblility of taking a pram on a bus, as you could not do so in the seventies when I moved away.
In Copenhagen we had got to around 1980 before it was possible to take a pram, push-chair or wheelchair on a bus.
I don't know if bus conductors would solve the problem of selfish passengers hogging seats or refusing to move in the bus.
Presumably, their wages could be paid by some of the funding being used on unemployment benefit right now, as conductors would either be recruited from amongst the unemployed or change jobs, leaving their former jobs available for someone without one.
Alternatively, you could reduce the amount of people paying cash to travel. Here digital bus cards and tickets bought and paid for on your smart phone have existed for years and since the first corona lockdown, no bus driver in Denmark will accept cash - you either use the one or other of the digital solutions. Or get off the bus and walk!
I imagine a bus conductor in certain areas these days would need a hotline to the police to deal with opstreperous customers, but as trains still have conductors and they can quickly notify the police, as can a bus driver at need, that should not be a problem.