Since procedures are different all over the world all we as pilots have to do is read the charts, so there is really no excuse for not joining the hold if no further clearance is received. No so difficult I think...
If there are airlines which don't follow the procedure maybe just contact the airline to remind the pilots of the procedure.
On another note; you were also writing about the numer of calls and in my experience sometimes ATC doesn't help keeping the volume of calls down. Often I check in on a new freq with the cleared level and hdg and instead of receiving an acknowledgement I'm told to maintain the level and hdg I just reported which we then have to read back again. Correct me if I'm wrong but would a "roger" not suffice (saving us from saying the same again)?