My parents were married in Pennsylvania in 1950. Despite the fact that I know all the details (when, where, etc.) I cannot find their marriage record online. Does anyone know why Pennsylvania doesn't have these records available? 

I have the same issue with my Parents.  Although I think I found my dads first marriage, the diviorce is not showing up and my parents marriage info is not.

I know there is privacy issues on some of this and another thing can be they just want to charge you to look it up and get you a certified certificate.

Ancestry.com has Pennsylvania marriage index on line that covers up to 1968.  If you can't find them in the index try using a wildcard search.  Maybe the spelling is off, or they just can't read the clerks handwritting.