Local jurisdictions have to compete with each other. If one town has a 40% tax rate because it's giving half the money to the mayor's brother and the town down the road does not, everybody starts to move out of that town and the economic decline ousts the corrupt politician. When the same thing happens at the federal level (with the money going to Lockheed and drug companies), "move to Canada" is a lot harder than "move 5 miles to the other side of the town border where you're already still a citizen."
This doesn't imply that small governments are never corrupt -- you can certainly find examples -- but it keeps the corruption in check. It adds vote with your feet as a means to avoid corrupt governments.
And the idea that everybody is paying attention to what happens at the federal level is contrary to evidence. Remember "we have to pass the bill to see what's in it"? It's too easy for lobbyists to sneak language into multi-thousand page bills that nobody is ever going to read before it becomes law. Whereas at the local level you shouldn't have multi-thousand page omnibus bills that have to address every edge case for everyone everywhere.
It's also easier for local muckrakers to prevent corruption when they find it, because federal corruption tends to have coalition support. The F-35 is a boondoggle but the people in the districts who receive the trillion+ dollars in tax money are very in support of the program and you're not going to convince them to cut it because the money comes from outside their districts. That doesn't happen at the local level -- the recipients are in the same local jurisdiction as the taxpayers -- so once anyone identifies the waste you can build support to eliminate it.
This doesn't imply that small governments are never corrupt -- you can certainly find examples -- but it keeps the corruption in check. It adds vote with your feet as a means to avoid corrupt governments.
And the idea that everybody is paying attention to what happens at the federal level is contrary to evidence. Remember "we have to pass the bill to see what's in it"? It's too easy for lobbyists to sneak language into multi-thousand page bills that nobody is ever going to read before it becomes law. Whereas at the local level you shouldn't have multi-thousand page omnibus bills that have to address every edge case for everyone everywhere.
It's also easier for local muckrakers to prevent corruption when they find it, because federal corruption tends to have coalition support. The F-35 is a boondoggle but the people in the districts who receive the trillion+ dollars in tax money are very in support of the program and you're not going to convince them to cut it because the money comes from outside their districts. That doesn't happen at the local level -- the recipients are in the same local jurisdiction as the taxpayers -- so once anyone identifies the waste you can build support to eliminate it.