Just answering your question from experience only, my in-laws have a 2000 Camry that can shift gears when ever you want. No ignition, no foot on brake, u can just slide it down.
I don't think it's a break. My 88 Camry did that too. Never felt 'safe' though. But probably normal?
I think the auto transmission differs. My old 92 Mazda 626 had different transmissions depending on the 4cyl and the V6.
They had different code names. Workshop manual probably specifies?
I don't think I gave any proper answers, sorry. But I read this thread and went "ooh! ooh!" *start typing* "ummm...hmm"