Having them vote on the price tiers of postal service package weights or Amtrak route schedules seem like a surefire way to bring the management of every public agency to a standstill.
In fact, the only example we really have of our congress being in charge of setting rules for a public agency is the tax code— and its a mess of carve-outs, loopholes, stopgaps (AMT minimums?) that most lay people need to use a certified professional to simply perform a required function ever year. And it’s consistently subject to political football, drastic policy changes based on whatever party is in power, and core issues that congress was originally supposed to solve by running it (like supposed to balance how much money it brings in against public expenses) are often ignored anyways.
The point of a republic is not to put every decision to a vote, but to elect people we trust to be in charge— which includes who they appoint to run agencies, etc. In fact, that’s where most of the president’s power Tiber policy comes from— and it makes sense why, since he’s the only person in our government we all have a say nationwide in electing.