At large companies, there's just a lot of coordination needed. Which means a lot of meetings typically. Probably more than there is needed but one of the points of a large company is having a critical mass of people pulling in roughly the same direction(s).

>also why is there a hard end time rather than a maximum time?

Depends on company, culture, and individuals. If you get through the purpose of the meeting, the meeting organizer may well say "Let's give everyone 20 minutes (or whatever) back." I do think that it's a worthwhile goal to default to <1 hour meetings.

In any case, agendas and thinking about how the meeting time should actually be spent is worthwhile.