How so? It seems to me that the City of Charleston is perfectly within its rights to impose a licensing requirement on taxi drivers as a way of ensuring that drivers, among other things, have the proper insurance. And it shouldn't be expected to simply waive this requirement because Uber is a big company that that says it offers insurance coverage for its drivers. Maybe Charleston would like to make Uber and its drivers demonstrate that they actually have that insurance, in a particular way and to a particular level of proof. Or maybe Charleston requires more or different insurance than Uber provides.
I don't doubt that there is an element of protectionism here as well. But that doesn't mean that there isn't also a public safety issue, or, regardless, that Uber is free to flout local law so long as it can pay the fines.
"perfectly within its rights to impose a licensing requirement"
How so?
I can think of two example of near unanimous modern agreement where lower governmental levels are not allowed to impose additional randomly purchased rules on subjects regulated at a higher level, its a thought crime to even suggest the rationale behind these historical issues:
Well of course there are certain licensing requirements that a municipality cannot impose. But you remain very far from showing that a license to operate a taxi -- an area that is subject to strict regulation in virtually every municipality in the U.S. -- is one of them.
I don't doubt that there is an element of protectionism here as well. But that doesn't mean that there isn't also a public safety issue, or, regardless, that Uber is free to flout local law so long as it can pay the fines.