Bus Rapid Transit calls when you are proposing a subway or a tram, promising great things at a low price. After you agree to settle for a shinier bus line instead of the nice, fast, reliable transit system you originally wanted, the value engineers get to work compromising the design, and you end up with... another bus route. Maybe it has a different color of paint this time.

It sounds like you were just going to end up with a mediocre, compromised system anyway. "Light rail" is still bringing us things like the Santa Clara VTA system at best, and the Virginia Beach "Tide" at its worst. Likewise cities with "real" subways include such luminaries as Atlanta and Miami. Have you tried to take the metro system in Miami?

Both Seattle, WA and Ottawa, ON built out dedicated BRT infrastructure that was later repurposed for light rail. So I wouldn’t say it’s always just a new coat of paint.

The downtown Seattle transit tunnel is an unusual beast; it was built from the start as a hybrid bus and rail system, though the city did not yet have any plan to build a train network. The builders designed the tunnel and its stations for train service and laid tracks anyway, expecting they would eventually be needed.

So... where BRT is a proposal to save money on transit by building cheaper infrastructure - a promise it can always keep, since bus service can be degraded as far as necessary to fit a budget - the DSTT project instead used the promise of future rail service as a motivation to spend more money on transit, building better infrastructure than they actually needed at the time.