Originally Posted by Nova Land
Are you aware that every member of congress serves on at least a few committees?
As such, when congress is in session and one sees a number of empty seats, then it is quite likely that the people who occupy those seats are most likely doing work in those committees.
And since it is not possible for them to sit in on committee work and sit in congress at the same time, then they have to be absent from congress.
Furthermore, since regular elections are held, then the members of congress are already subject to periodic review of their congressional duties.