The reasons for farm subsidies are… Debatable. If you keep food cheap people don’t notice currency debasement as much. Personally I think it might make more sense for prices to rise to a point where farmers are profitable without subsidies. Those subsidies are value extracted from the tax payer anyway… You’re paying for it.
You’re right too in that buses and trains are a lot cheaper and should always out compete cars. How much do you think fares would have to rise to make public transport self sufficient ? Make it so it funds its own expansion and service improvement.
The Toronto Transport Commission is my local example. From what I can napkin math they get about 1 billion dollars in subsidies per year from the city (maybe some provincial and fed money too… I rounded up generously). They collect a little over 700k fares a day. Wouldn’t take much of an increase with like almost 250 million fares a year to close that gap.
Privatize the roads and have cars users pay their share of that infrastructure cost and get the burden off of working people and I bet a small share increase would be pretty affordable.