How about law as a subscription service? The maxim is if it has value in people’s eyes, then people should be willing to pay a monthly fee for it, voluntarily and without coercion.
In addition I don't know enough about traffic safety to figure out what the best speed limit is for certain roads, nor how the road should be constructed (especially given local environmental conditions, estimated use etc). It's cheaper overall to outsource it to people who know. Otherwise how can I decide if I want to subscribe to that safety rail at the edge of a certain roadway?
Says you.
Damn near every government (from local to national) has a charter more along the lines of "do these specific mostly administrative things that we agree are best done at this level".
Otherwise, if it's truly pick and choose... how much thought did we give to this? :)
Will everybody pay equally for each law, or rich people pay more?
If rich people pay more, and they decide they don't like the tax avoidance laws, will they be disproportionally funded?
If everybody pays the same, this will be proportionally harsher for poor people.
Most people will not pay for 97% of the laws which may be overall important but don't impact them directly - e.g. I live in Toronto so don't car about fisheries laws, etc.
Some people will not pay for laws they personally don't want to abide buy - from speeding tickets to financial regulations to fitness of goods and services etc.