Not really true these days. The "Expedia" companies (Expedia, Orbitz, Hotwire, Travelocity, Ebookers, etc.) all warn you and provide you with upgrade options to main cabin and other fares. See screenshot below. Priceline group (Priceline, Kayak, Cheapflights, Booking.com, etc) does as well, but seems to be a bit more hit and miss. I just priced a DTW-ORD itin on Priceline, and was presented with upgrade options for AA and UA flights, but not DL for some reason (although, I just retried on booking.com/Kayak and they did offer one for DL as well).
They're charging a $50 premium to select seats (and get medallion benefits) on a 90 minute flight? I remember back when people said that E fares weren't
that big of a medallion downgrade
