For UA / CO, this is so. US does not offer a lifetime status (though I hear you get a handsome photocopied certificate and possibly a luggage tag when you reach the 1MM mark). The thing about US is that although it is in many ways a legacy carrier, the crew in Tempe aspires to become a LCC and prices and runs the operation accordingly.

OP, you have come to the right place to learn about airline stuff. I fly quite often and have still learned a tremendous amount from these boards.