I've been an advocate for Bidline for cabin crew for years for the reasons that have already been stated. In fact, it is used by a number of US carriers for their cabin crew. Perhaps if BASSA had been a little more flexible in the past, this could have been an option.
I work for a US carrier and can't think of any of them that don't use bidding.
The bidding system is a real bone of contention over here as it's only of benefit if you're senior. At some of the carriers, NWA, UAL etc., reserve is running into 15 years at bases. That means you can only bid for your days off and pick up the slack that seniors drop, call sick on etc., We're paid a base guarantee of 75 hours but rarely will you go over that.
At my carrier seniority has stagnated since 2001 and I'm still on reserve and despite being fluent in English, Spanish and Italian, have only flown two international trips in the last year!
How does bidline work? Are the lines posted and you bid in preference or is it more similar to DL whereby you do preferential bidding?