I said sorta this in another thread when replying to Bob, but the nice thing about blind-spot monitoring (which I love, BTW) is that it tells you at a glance when it's NOT safe to go. Light's on, don't bother merging, plan an alternative course of action. Plus, there have been a number of times while driving that, even after my head check, impatient idiots have raced forward to my side, with the light alerting me at the last second to stop merging. It takes a second to do a headcheck, but stupid is instantaneous.
Additionally, in an emergency, if I absolutely have to swerve without a chance to turn my head away from the road, knowing that I can't swerve left but *might* be able to swerve right beats knowing nothing at all, i.e. BSM isn't something drivers should use in routine merging, but when things go south in an instant, even an imperfect technology gives you better odds than a coin flip.
Technology is best used as a ladder, not a crutch. :thumbup: