No, they have to show up, and then they can object to unanimous consent. Then we need to have votes, and they can require 60 votes to get just about anything done.
Most of what happens in the Senate now happens behind the scenes. The majority and minority do "whip counts", figure out whether there are enough votes to pass something, and then get together and decide to just let things go without votes. Then they take the floor to make unanimous consent requests.
They have votes on everything they want to be recorded about, or where votes aren't quite known.