In many places outside urban cores in the US, the rules are such that the amount of parking created is far in excess of demand. You could try and rent your spot, but it would be pointless. Inside urban cores the parking is frequently underground and gated off so that it makes it hard to rent out without breaking the security rules for your building.

At the last place I lived in Vancouver, BC there was 2 levels of underground parking for 3 stories of living space. It is absolutely wild to think that a building along a major transit corridor was required to reserve 2/5 of their building for private vehicles in a city that is famously progressive with transit (for north america)

That's interesting, but I doubt it would be allowed by most apartment leases, and I think for townhomes, many people wouldn't want some rando parking in their garage.