Originally Posted by GUWonder

That's your experience, but that's probably just because you've been using UA's program when it didn't make sense to do so if earning miles was of primary interest to you.

For years now, I have systematically gained miles from a large number of Priceline bookings on UA-operated flights such that it would be an exception if I were not to get miles for the UA flights acquired through bidding on Priceline.