> Taking this to extremes, why would politicians not sneak every crazy wild idea that they have onto this bill if it's a must-pass bill?
They try; there are various constraints:
(1) Individual members can't just stick a rider onto a bill, riders are amendments, and are voted on.
(2) Riders are, in effect, a strong-arm negotiation tactic between one house of Congress and the other, or between Congress and the executive -- a gamble that the other side sees the other provisions of the bill as "must pass" enough to accept the added conditions. But those gambles can be wrong, resulting in neither the main bill or the added provision getting passed. So, the biggest incentive to add non-germane riders is to a bill you are less concerned with passing than those you are trying to get to accept the rider as a precondition for the rest of the bill, where them rejecting the rider is more unattractive to them that it is to you. If you really think its a "must pass" bill (rather than just wanting others to think that so that they'll accept the rider), you won't want to risk causing it to fail somewhere in the process because the rider you attached was unacceptable.
Unless you want the political fodder to say the other party is also willing to shut the government down. If you don't care about shutting everything down you can put horrible things in a must pass bill.
If you don't care about shutting everything down, there is no such thing as a "must-pass" bill; at least, the fact that not passing a bill would lead to a shutdown doesn't make it must-pass if you don't care about shutting everything down.
But I think you are agreeing with what I said, that its more attractive to attach riders to something you think your counterparty sees as "must pass", but you do not.
They try; there are various constraints:
(1) Individual members can't just stick a rider onto a bill, riders are amendments, and are voted on.
(2) Riders are, in effect, a strong-arm negotiation tactic between one house of Congress and the other, or between Congress and the executive -- a gamble that the other side sees the other provisions of the bill as "must pass" enough to accept the added conditions. But those gambles can be wrong, resulting in neither the main bill or the added provision getting passed. So, the biggest incentive to add non-germane riders is to a bill you are less concerned with passing than those you are trying to get to accept the rider as a precondition for the rest of the bill, where them rejecting the rider is more unattractive to them that it is to you. If you really think its a "must pass" bill (rather than just wanting others to think that so that they'll accept the rider), you won't want to risk causing it to fail somewhere in the process because the rider you attached was unacceptable.