Just also as a note, you can create suburbs pretty easily where bikes use paths or whatever. I live in a suburb where I can ride 15 kms to work without riding on roads. The subsidy for bikes would actually be really low.
You should look at Cost benefit analysis, there was one made on Copenhagen. [1] Bicycle infrastructure usually gets you 6x-12x on the invested amount, getting a 1.2 CBA is ok, 2 is amazing.
Bicycle infrastructure is often destroyed by those other investments and that is usually not counted as a con. But it is just too cheap to build bicycle infrastructure to be interesting.
The subsidy per passenger mile in the US is :
0.019 for road transport, 0.021 for air transport, 0.710 for Amtrak and 2.300 for transit.
From : https://ti.org/antiplanner/?p=22592
Just also as a note, you can create suburbs pretty easily where bikes use paths or whatever. I live in a suburb where I can ride 15 kms to work without riding on roads. The subsidy for bikes would actually be really low.