Generally, cleaners tend to do work that isn't in the normal everyday chore category. They tend to take the place of things that are regular weekly chores, like cleaning the loo, mopping, etc.
If you want them to do things that are daily chores (like dishes) or more occasional chores (like window washing), it's best to let them know explicitly. There are also categories of work, like laundry, which aren't expected but can be negotiated. There are complicated historical reasons for this, but practically, a lot of people want their laundry to be done by skilled practitioners rather than someone who might accidentally shrink a sweater or put silk through the machine.
If you want a housekeeper rather than a cleaner, he or she would tend to do a wider range of things.
You seem to be thinking that your cleaners are mind-readers, which is unreasonable. If you want them to do things, you should let them know, either in person or in writing. And it's always a good idea to keep a list of extra items in case they finish early on other things.
It is of course not unreasonable to want any employee or contractor to do a good job at their job. If they're routinely leaving half an hour early not because they're brilliantly efficient but because they've done a half-arsed job, then you should certainly reconsider their employment. But I'd make sure that I was being a good employer, too: clear, straightforward, and anticipatory.