You're missing that these bins _were_ used in IRA bombings in London, and it turns out that the flying shrapnel from a heavy exploding bin is quite dangerous.

Lighter-weight solutions were later introduced that limited the ability to place large objects in bins, or substituted large bins for clear plastic bags supported on a frame. These are still reasonably prevalent, though there could definitely stand to be more of them around London.

One can usually tell which countries have experienced terrorism, or at least pondered it, by the type and construction of trash receptacles. America has many tens of thousands of thick decorative stone, concrete and metal public trash receptacles vulnerable to bombings. When that happens, they will be gone, but rarely before.

Last time I was in Victoria Station in London, there was one alumin(i)um hoop with a clear trash bag, emptied constantly.