For anyone in the UK interested in getting a bidet: most normal bidets are illegal due to our water safety backflow prevention regulations. As a minimum you need a break tank - a double check valve isn’t sufficient.
There's no risk of the spout sitting in and siphoning dirty toilet water it back into your supply. I'm neither a lawyer or a plumber but these seem like they might be okay.
In many places in Europe tap water is safe to drink. However, hot tap water is not.
The regulations mentioned by GP might protect safety of the cold tap water from intake of hot tap water. Which is easy to do unintentionally when mixing hot and cold water.
The separate taps thing is more because it costs to replace a sink. So even if you put a new boiler in an old houses lots of people aren't going to replace the fittings in the kitchens and bathrooms at the same time.