How do loads of cities overlap state borders?

1. If a large city is bang in the middle between two states like for example, Kansas and Missouri or Tennessee and Virginia. Doesn’t it get real weird like with the different state laws and taxes and stuff, how does all that work?

2. When you cross borders of states does it work like country borders but relaxed? Are all states the same in border control or are some relaxed and some strict?

My bad if this sounds stupid just seems real interesting and alien to me how it works.