Edit: Note the absolute phrasing of the parent comment and that the spray force in a strong downpour isn't much less than what's done with firefighting planes in situations that call for that level of pressure.
This video doesn't prove your point. Not only are they actually not directly under that, but this is spread over a much larger distance than trying to target the cathedral would be. They configure their release to spread over a larger area than that.
That's much more volume at once in any one area and much closer to the subject (so less time to dissipate) than any of the actual flying water tanker videos that have been posted.
The rain falls over an extended period of time, not all at once as one glob. Only several drops are hitting you at any given instant in the rain, so you are only subjected to minuscule amounts of force at any given instant.
The difference would be like standing in the shower for 40 minutes, versus being hit my an entire tub full of water going at the same speed all at once.
I remember during the Khan Academy controversy a few years back, an educator commented on reddit about the difficulty in teaching some kids about rates. Some kids just don't get rates. They think of speed as something like "a feeling of intensity." They just don't have an abstract, generalized understanding of "N things per unit time."
Think about that for a moment. Think about all of the potential for miscommunication.
Yes, but the water sprayed from those tankers isn't much more intense than a severe downpour plus wind. The branches aren't snapped off the trees they're sprayed on here and people are standing right inside it: https://www.youtube.com/watch?v=87hfWatbVPY
I'm comparing strong rain to water plane spray. Maybe the output of some would be too severe, but clearly some are suitable.
Edit: Note the absolute phrasing of the parent comment and that the spray force in a strong downpour isn't much less than what's done with firefighting planes in situations that call for that level of pressure.