That's certainly been my experience although I don't fly TATL as often as you. Actually the price differential between the cheapest and the most expensive is not vast anyway. It may also depend somewhat on route; I never fly into CDG and they may make a greater effort for those flights.

In the days of the separate "Vinum" program it was much more obvious. They often featured fine wines on the menu which after the salad days of the program were never actually served.

At the absolute nadir of BE wine service I experienced both heat damaged wines and the exact same selections as DL domestic, which at the time were from a cut-rate California producer that made Charles Shaw look high end. Despite my lack of enthusiasm for the current selections, it has improved greatly since then.