A lot of cities this size have a separate traffic enforcement section apart from regular police (the old "meter maid" force). My own, which is about half the size of Minneapolis, has one. This would not be an especially onerous task on them since they are doing it anyway. It may end up being "useless" in the end as far as fines go, but it might have a little sting here or there.

Sure, but there probably weren't any "meter maid" cops there. Those looked like regular Chicago PD cops.

As noted in the prior thread, this would have zero sting. The federal government doesn't have to follow state or local laws in the conduct of its official business. Federal agents are subject to state law when they're not actually performing federal governmental functions (ie. they have to follow traffic laws on the way to work), but state laws cannot limit or impede those folks from actually performing their duties. The Supremacy Clause isn't limited to just statutory conflicts between state and federal law - states can't impede or restrict how federal officials perform their official duties within the states.

Again, I've run into this a bunch of times in my zoning and land use practice dealing with federal buildings. Basically, a federal building can ignore virtually every state and local regulation - they don't have to follow zoning, building codes, fire codes, any of that. They sometimes do, of course. They like to maintain good relations with local government, and if the building is ever going to be sold out of federal use and ownership it's helpful if it complies with as much of the local code as possible (the next user will have to comply). But they don't have to, and you'll often see federal buildings that have features that don't meet setback or signage rules.

So there's literally nothing that sticking a ticket on that truck would do to ICE - either for the plate or for the illegal parking. It would certainly be more of an inconvenience to the city police than to ICE.