Government Mandates and other Paradoxes

Anybody want to give me a reason that mandates from the federal government are constitutionally acceptable? I bring this up since it’s clear that’s it’s absolutely part of our current government which couldn’t operate without them. And if we’re crossing the line this far, shouldn’t we be honest and just say scrap the constitution altogether, since it’d be much more efficient to operate directly.

Federal mandates are the central government proposing regulations that the states could adopt, and giving large gobs of money to the states that do this. The most famous example being federal highway funding that a state only gets if their speed limit is max 65 mph and the drinking age is min 21 years, both of which were the source of much anger.

This is basically how the entire Department of Education exists, since hey, the constitution specifically forbids the federal government from running education. But our populace demands some universal rules and funding for our school system (which makes sense to me; the state of Mississippi should not teach their kids from the same tax base as the state of Connecticut if we have any interest in any child unfortunate enough to be born in Mississippi to have a fair shot), so we have complicated systems where the US says all schools must have certain special education facilities, and gives the states money to build them, money which the states become dependent on for building all their schools.

(And the “voluntary” nature of these mandates seems bunk once you realize that both governments are competing over the same tax base.)

Still, how can these pass the “laugh test” by any constitutional scholar or federal court judge? It’s like (and no less constitutional) than the government saying “We can’t establish a Church, but we can tax everyone, and give you $10,000 if and only if you are Baptist”.

Unless there is something I am completely missing here. Please do enlighten me.