JetBlue asks for rule waiver, plans to keep passengers on tarmac for 3+ hours
blog.flightcaster.com
blog.flightcaster.com
I'm guessing that JetBlue thinks the answer is "yes, sometimes". They're a low-cost operator. Turning the plane around is expensive, and the cost, I'm sure, is entirely on the operator.
This is a problem only because ATC can't tell one hour ahead of time if the expected wait-time is 30 minutes or 3+ hours.