Krzysztof Reszka wrote: But why, the regulations do not prohibit having a socket under the sink
Indeed, the standard applies to a bath, shower or swimming pool, but there is no word "sink" or "kitchen sink" in it. Regulations and rules, however, indicate the minimum distances between nests and "wet zones". Anyway, even the lack of detailed records does not exempt anyone from a bit of common sense. Let's take care of safety for ourselves, not for standards.
Krzysztof Reszka wrote: The insurer has nothing to do with it
I don't think you're quite right here. This is an excerpt from papers that deal with a similar situation:
No checks required (mentioned above)
may be the basis for refusal to pay compensation. However, if a fire (or other event) occurred as a result of a short-circuit in an incorrectly arranged or operated installation, the insurance company may indicate failure to fulfill the obligations by the aggrieved party as the reason for evading the payment of the benefit. However, if the event had nothing to do with the condition of the installation or chimneys, the insurer cannot base the refusal on the fact that the building was not inspected in a timely manner. The text comes from one of the appeal letters after a refusal to pay compensation.