That's why each bill goes through a committee. Once finished, committee members present it, Reps pass it to their aides to read and comment, then they read it with the notes their sides provide, when done right.
Not all bills are this long, but this bill covers a lot of territory. But then, a rep should be able to read and comprehend those bills. This is why most elected officials are members of the bar association or have law in their backgrounds.
Best piece of legislation I've ever read was in the Ohio state legislature concerning making Hang On Sloopy the official rock song for Ohio. If you have a few minutes, Google it. Wikipedia had a very good article on it. The legislation is less than two pages. You'll love it.