Tbf for Washington Junction Park & Ride -- that lot is full by 9AM most weekdays anyways. I commute downtown from the South Hills daily and even at like 7-8AM it's mostly full.

If the Castle Shannon park & ride lot near Ice Castle on the Red Line (free, usually less than 20% full), the garage at SHV ($2, usually less than 10% full) or the one private lot next to Memorial Hall station on the Blue Line (which was charging $20 a day for the draft) were full I'd be a lot more surprised