I am not certain if the reply function to an answer sends an alert to the poster- and I still had this page open- so I noticed Kate's follow up question.
I am treasurer for my Manhattan condo- so I am able to answer your question.
Let's be clear- first off, if you buy a condo or a coop- you are an owner- there is no landlord. Assuming there is no sponsor (typically the developer of the building) still involved in the building- the Board of Managers is made up of fellow owners that volunteer to help run the building (typically higher level policy decisions) . The Board of Managers in conjunction with the Managing Agent (which deals with the day to day management of the building and may provide guidance on policy decision) figure out the cost structure to run the building.
The monthly fee's that you pay for things like elevator maintenance, the super, heat, water, etc and compliance with NYC building code requirements that change every year- and are extremely expensive. So when the Board of Managers increases the monthly Common Charges or Maintenance, it's rarely because they want to but because they have to. The cost of Water alone has been increasing by 15% a year for a number of years now. Remember the Board is compromised of fellow owners- so they are voting to increase their own costs as well.
If you buy a co-op, most buildings have a mortgage- which helps the building undertake large projects easily. Maintaining a building in a city is far more complex than maintaining a townhouse community out in the suburbs. This mortgage component is seperate from the mortgage you would seek to purchase an individual apartment. This is different from a condo, where it is very uncommon (though not impossible) for the building to take out a loan/mortgage. Typically in a condo the building should either have reserves to account for these large projects (with the money funded as part of your common charges) or via a special assessment. One way or another if you were to compare two apartments side by side- identical in all ways except one is a condo and one is a co-op, the monthly maintenance vs. common charges+property tax should be rather similiar.