You'll forgive me if I don't write with the same level of aggression
as you. I'm trying to keep my blood pressure low.
In England, where I live, home builders have been installing cold
water tanks for a long time. The logic: they make a good back up in
case of mains water loss. I've lived and worked in buildings with cold
water tanks for years. I know a bit about them. The cold tap (faucet)
in my bathroom sink runs with half the pressure of the hot tap. No,
they are not mixed.
The hot and cold water pressure is not balanced in my bathroom.
That aside, I realised the root of the problem. For the benefit of the
non-aggressive posters of this group, I'll share it. See my earlier
thread about my cold tap. (The tap died. But the hot tap was okay.)
This afternoon I spent a few minutes inspecting my old shower
cartridge. Grit all over it. Just like the cold tap cartridge my
plumber replaced last week. The problem is the cold water tank.