Find one LRT with at grade crossings in the world with 2 minute headways: Budapest
Low operational overheads are sited as a concern for having an LRT from Arbutus to UBC. "Find me one example of a system with at-grade crossings that runs with 2 minute headways anywhere in the world" is a common refrain.
Also, there are costs to consider, however the operational costs will be less than Bus BRT with multiple berths. The costs will be higher than running low frequency with a longer train (however I'm guessing the next argument will be..show me one train that is as long as the one planned/necessary for the UBC stretch...), but that argument is tangential.
More to the point, Budapest's L4 and L6 tram lines is only one line which differ by two end stops. It now operates as low as one minute headways. It is Europe's busiest tram. Interestingly, it bought new trains in 2006 @ 60m (fairly long) and the #4 and #6 trams are famous tram lines that link all the major metros in budapest. It's length is 8.5 km and it used to take over 30 minutes, but as of 2012, traffic signal priority was implemented on the ring road and it now takes 29 to 30 minutes with average speed of 18km/h with station spacing of 400m (19 stations in 8.5 km with 29 minute run time). These characteristics are similar to Vancouver's.
It is known as the ring line.
"Budapest established its tramway system in 1887, and its ring line has grown to be the busiest tram line in Europe, with a tram running every 60 seconds at rush hour." -
https://en.wikipedia.org/wiki/Tram
"This is really one tram line, the only deviation between the two occurring at the terminus of the route at Újbuda központ (4) and Morícz Zsigmond Körtér (6)." -
https://likelocals.blog/the-complete-budapest-transport-guide/
"Traffic lights along central Budapest’s outer ring road (Nagykörút) have been adjusted to give priority to trams, cutting journey time on lines 4 and 6 by two to three minutes."
"...trams will also run more frequently from February; up from 28 to 30 trams per hour in peak periods."
"The Municipality of Budapest initiative was implemented by BKK in order to cater for rising numbers of public transport passengers (already between 7,000 and 8,000 in peak hours compared to 3,000 individual vehicles)."
"Traffic lights at a further 68 junctions were reprogrammed to support 60-second intervals between trams (rather than the earlier 90-second intervals) and to cut journey time from 32 minutes to 28-30 minutes." -
2012
https://www.eltis.org/discover/news/priority-trams-central-budapest-hungary-0
https://en.wikipedia.org/wiki/Trams_in_Budapest