There's almost certainly no political appetite for this in the US right now, but (in theory) would it be constitutional for a federal law to prohibit state and local governments from selling taxicab licenses (the famous medallions, which are valid in perpetuity and resold on the open market) and instead mandated that the state/local authorities directly lease non-transferable licenses to taxi operators/driver? (The latter scheme is common in Europe.)
The Commerce Clause, in its broad interpretation seems to allow such a law. For example, one could argue that since companies like Uber operate nationally, taxi licensing is now a matter that needs a uniform, federal framework. I could be missing some of the finer points relating to the (varying) interpretation of the Clause by the (various) Supreme Courts over time. Also, could such a law run foul of some other state rights?