[goldenbeet]

I know literally next to nothing about this, so beware my comment. However, I'm pretty sure that " tens to hundreds of senators or representatives collaborate" is not a thing for bills.

It's typically a small group of people who create the bill. (Like a Senator and their staff) It gets proposed to a subcommittee who reads it (I believe they also give feedback) and then accept/reject it. If accepted it then gets passed to the entire Senate/House for people to read and accept/reject.

If you're curious about how the actual writing occurs, I'm sure its nothing special. Just like writing a group paper in school.