I think few Congress reps of any party read completely read a bill under consideration, and some may not read a bill at all. If anyone does read a bill it is persons on the Congress reps staff and they are all well indoctrinated college educated persons who often arrive at their jobs with the biases and prejudices they were brainwashed into in college.
What does the Congress critter think they are voting for?
They think they are voting for what is the public description of the bill, not what is actually in it.
“I was elected to lead, not to read.”