In the UK there is a split between England and Wales and Scotland. “southern” UK trespass is a civil offence. Scotland it is criminal.
So in southern UK trespassers will most definitely not be prosecuted (the railway and power plant property are, iirc, the two exceptions because they have by-laws) but may be sued for damages, in Scotland they can be prosecuted.
Arguments against… Wheelbarrows of troubles from Putin…