I was in YUL a couple weeks ago, travelling on UA metal with 1K printed on the boarding pass. The nice lady at the maple leaf lounge asked for my card, which I had forgotten. She punched my MP number in manually and told me she was making an exception but I needed my card for entry next time. She made comments which indicated that she knew from my boarding pass that I was 1K and thus qualified for entry. I could see others not being so willing to make the exception. So LH is not the only airline that requires the card.