They are still free loading on infra they have not paid for. I see no reason not to make them share the cost too especially for the space they need to be dedicated to them.
The local communities paid for that infra. With zoning laws and during the development of subdivision. The cost of land for their lot reflects the additional land cost and and infra developed. They also pay utility connection fee so the city can build plumbing/sewage infra.
Also, homeowners pay 3% property tax (Texas). This pays for everything local, schools, roads, police, parks and a ton of other things.
Homeowners also pay their HOAs, while not as much as property taxes, this covers a ton of things within their subdivisions.
The super rich are free loading on all of this infrastructure.
My point is that pedestrians don't directly pay fair share of costs. Just like trucks don't directly pay fair share of costs of roads. Scenario is exactly the same. Or really much much worse with pedestrians. There is no tax they directly pay for the roads. I see no reason why they should be treated different from trucks.
This could be solved by tracking those activities. Say GPS tracker attached to everyone. Decide certain beneficial point and then going under it or too much over it would result in losing credits.
This has nothing to do with the topic. Cost of maintenance due to usage for pedestrians is effectively zero. Putting more effort into quantizing that maintenance is separate from the infrastructure investment.
This (micromanaging) line of thinking toward maintenance is degenerate social policy.
ie Treating the cost of someone receiving benefits for which they did not pay (or otherwise deserve) is a catastrophic enough to desire more spending and bureaucracy to withold the benefit.
I hope you were just making a snarky joke as there is effectively no road damage done by pedestrians and cyclists.