So he goes through the catalog of typical off the shelf solutions that exist in his trade, selects a reasonable one and has it installed. 6mo later his inbox gets blown up by the same million Karens screeching about how the barrier made the bike path suck.
A large subset of the public is made up of people that don't understand that everything is tradeoffs and think they can have their cake and eat it too. And because these people can't wrap their minds around the tradeoffs it's impossible to have the adult dialog regarding which tradeoffs they dislike least that needs to be had if the least worst solution is to be reached. There's no winning when dealing with this kind of customer base unless you creatively define "winning" to exclude customer satisfaction. But when you do that you get other failure modes. You can sometimes money your way around the problems but that's just a constant factor improvement on something that's exponentially crap.
Like the "concrete pigs" you mention. Often not marked properly, and cyclists have to slow down to a crawl to pass. Often 90% of the road is blocked with a boom barrier, and pedestrians and cyclists all have to share the remaining part to squeeze through. That only increases conflict. Also pretty hard for bigger cargo bikes, wheelchairs etc to pass. During winter, the booms are opened for the snow plow and then closed. Which means that as a cyclist I still have to cycle around on the un-plowed part...
It's insane the lengths one has to go to avoid cars destroying everything.
Edit: An example pic https://imgur.com/a/FmDd5Ve Nice wide road, have to close it off with a boom because of cars. Pedestrians and cyclists have to pass on the icy parts...