I'm still not fully understanding what's going on here, and I'm american. Could someone who is more educated in politics of the US explain to me why this shutdown is allowed to go on for this long, and why there is no law in place for 'if the congress cannot come to an agreement, X shold happen'?
The law says the opposite: agencies are legally prohibited from carrying out any nonessential work without explicit continuing funding. Look up the Anti-Deficiency Act for more info.
As for why it continues to be this way, it’s because politicians have found the threat of a shutdown to be a useful bargaining chip. It’s a little bit like nuclear weapons: they’re pretty bad, but at the same time people stand up and listen to you when you threaten to use them.
The problem is that we now have an idiot in the Presidency and too many cowards in Congress who don’t want to bypass him.