There are limits on the laws of a State when it involves inter-State commerce.

The US Supreme Court recognizes a general principle that you can transit a State with things that are illegal in that State. An individual State cannot impose a de facto ban on commerce between States, which includes the right to transport goods through a State in the normal fashion regardless of the laws of that State.

Yes because people can't be expected to make expensive modifications to their vehicles while visiting another state. And the law in Minnesota is ridiculous especially in situations like a Crosstrek vs an Impreza. They have the same body but the allowed tint levels are different because one is classified as an SUV and the other as a station wagon. I could lift my Impreza and make it look exactly like a Crosstrek, but the tint would still be illegal. I find that funny.