Obviously the letter box and fire safety equipment is ludicrous, but some of the others seem to be for commercial insurance and liability issues. And I still support the fence around the pond

All of this is blamed on 'health and safety gone mad' as if the Health and Safety Executive or the law are responsible for these ludicrous decisions. In fact the HSE are constantly having to bust myths that they have decreed things when it is down to either excessive misinterpretation or, probably more commonly, being used as an excuse for laziness. To put it in context we have near us a site where ancient buildings have been rebuilt (Saxon, Iron Age, Roman, etc) and when they have open days they have activities for children to take part in, up to and including the use of axes. The HSE are perfectly happy with their risk assessements and the measures they have put in place, and children happily hack away at logs with bronze, iron, and steel axes. https://www.hse.gov.uk/myth/