Some PP mentioned that nowadays there are not enough park rangers and others to enforce some sort of conduct.
That's part of the problem, that these rules are not necessarily ingrained in people (about what you don't do in public, for various reasons (health, safety, ASBO, noise pollution....)), they are not forwarded in some families and I wouldn't neccessarily say to add it to the school curriculum like the 10000 other things schools are supposed to teach instead of parents or caregivers.
On buses and trains there are n't any or not many conductors anymore who would notice that and deal with it, as the driver obviously can't do it themselves while driving.
All the extra staff has been reduced for cost-saving measures but without some external checks apparently people do not inherently care for that.
But comparable to the schemes about litter picking, councils could perhaps start campaigns on other topics like noise, too. Something where they reach a large percentage of the population, so that it's more about prevention than individually contacting every source of noise. That could help with the social awareness.
The noise raises stress levels (more costs to the health system and of course to the individual) and annoys wildlife. One important aspect of it (as provided by the examples here) is that the others cannot choose what to listen to and that it carries through the surrounding and through walls and windows.
What people did in the decades earlier is probably a different kettle of fish as the speakers weren't as loud and powerful as they are now, even the small portable ones and not everyone had one.
I would say it can also lower productivity when others can't focus as much or intrudes on the downtime of others that they need to relax, too and to work productively the next day. This then has an economic cost, which is probably the only argument to get gears in motion in this political environment.
As for the builders, there is a "Considerate Constructors" scheme, and one of the points is to not play music as loudly, but I can't find it on the page right now, but I remember to have seen it.
www.considerateconstructors.com/about-us/the-code-of-considerate-practice/