I generally think more can be done. But your post is simplifying much. Every way into German is literally all of it, except small parts in the North which are

I generally think more can be done. But your post is simplifying much. Every way into German is literally all of it, except small parts in the North which are sea. Germany is all land border, essentially. Too much to control with any army. Ask Americans how that wall with Mexico is going. Like that. Also, when Europeans speak of border posts, they mean some scanners on otherwise open highways. However, this doesn't mean that there's some sort of restriction outside of these border posts. Shutting them down doesn't mean anything is closed or whatever. You can cross into Germany literally anywhere. There are no borders, not in the way that you think. When I was on the wrong side of the Dutch border soon before a local lockdown during a shooting, but was in a hurry, I just went through a village road. Heck, there's even towns that practically cross borders. How are you going to control every street? Right now, borders to several countries ARE closed. Does it stop most people coming to Germany? Nope. There are also political considerations that are too complex to discuss here. Livelihoods across borders depend on coming to Germany, as well as a lot of pan-EU traffic. An overreach is likely shut down by courts, in the worst case by an EU court, which opens a new can of worms. It's not as easy as you think.