With strong personal opinions, I must say “BRT” is not “non-controversial”. You will end up with people misleadingly tagging it for systems that call themselves a “BRT”, but isn’t one in any definition. Or there will be many arguments over them. Then it’s not really that useful. Shouldn't we make rules that suit each country's road system? - #45 by oruk09
Even if you use brt=yes to mean anything advertised as “BRT” somehow, using it on both qualified and unqualified services dilutes the meaning. It does a disservice to both.
My perspective is to describe verifiable criteria Highway=busway on non-BRTs - #37 by Kovoschiz
Eg stopping_pattern= is something specific. passenger= is already used on railway= and route=train etc, instead of the generic scope= proposed before. Proposal:Differentiation for routes of public transport - OpenStreetMap Wiki
If the name= contains BRT, it can already be searchable in theorey. To describe the functionality, I love the historically accurate Japanese, and existing Korean terminology “trunk” bus. So we can describe whether the route=bus is performing a backword, main, competing alternative to rail, auxiliary, or rail feeder role, etc.
Recently, there’s a question on articulated buses as well Talk:Key:bus class:length - OpenStreetMap Wiki