You are objectively wrong. Public transit scales the same way free and paid (i.e. based on demand). The cost for free countrywide public transport in a country with very high quality public transportation (so not the US) is about 8k per person, per year. This isn't some insurmountable amount of money - it's not even particularly costly when you compare it to what the infrastructure costs are for cars (mostly related to accident mitigation. Especially bad in the US).