They have Maid Service as an Hotel?

In most cases, the apartment have maid service once a week, depending on the apartment, because it is a decision of the apartment owner, and generally it's included in the rent.
In case it don`t have it or you want more days of maid service ask for it and their costs.

Why we can`t see an Apartment before renting?

In most cases, for not saing all, the apartments you see on every site, have their particular owners. So, the companies doesn`t have the key of the apartment until the day a guest get inside. Plus the apartments are many times occupied by other guests, so they can`t bother them showing the apartment.