I like to think that the bar is actually very low. Like (moderate) people in a neighborhood proposing to maintain more natural-style parks but being held back because a city has to spend much of their time on and needs to CYA against foaming-at-the-mouth environmentalists who will never find anything good enough. Those moderates aren't as invested as the zealots, so they won't push very hard. It's the problem of the silent majority - people who don't really care but wouldn't mind are held back by those the few who are hardcore and don't think small progress is enough right away.

As for concrete plans - I've seen so many, but none of them are 'big' enough to really wow anyone. Small scale renaturalization projects being stopped because they don't provide the right habitat for this particular type of frog or whatever it was so now nothing's done at all and the whole coastline is eroding again (no frogs now either!); a pensioners' hobby group who build wild bee housing but the spots where those were supposed to be put wasn't optimal, so they were moved, demotivating everyone so the whole thing stopped. The 'fruit trees in cities' thing, drowning out those who just want something nicer than what there is now, and would be willing to invest some time or money, but not if it means arguing 50-page reports on why this tree over another. In all cases, probably if there had been someone with enough determination some solution could have been found, sure. What the zealots fail to recognize though is that they're only antagonizing those who would be favorable to a moderate version of their ideas, one that wouldn't cause them too much inconvenience.