Yes, I know such checks aren't perfect - but at least they might discourage the real nasty ones.
It's probably because the lack of checks makes it easier to gain access that he came here.
I reckon it's only a matter of time before things start going the way they have in UK.
Example, In UK I offered to accompany my sister and her young son on a school trip to the zoo and to help supervise. I was told it wasn't possible because I wasn't CRB'd (crime check). I pointed out that I was, but was told it probably wasn't for that particular region.
Poland, I work with kids in a school (no check), I have been supervisor of groups of young teenagers (no check) and been the only adult with them on international bus travel (no check), I've run theatre workshops (unsupervised) with kids and at risk adults (no check).
British system is a bit tight-@rsed at times but it's there to protect people. Polish system is still surprisingly trusting.
Foreigners have to be screened more before they are employed in Poland.
Is this a recent thing? When I moved to Poland in 2002 I walked straight into a job at a (non-public) Liceum/gymnasium with no checks and without even having a teaching qualification.
On another subject raised, about camps etc, a few years ago we ran a summer camp in a local holiday centre. The centre was also hosting a group of martial artists from warsaw. While our kids were staying in the centre's rooms, the MA guys were camping, as were some youngsters from a sailing club. One man attached to the MA group started harrassing some young girls in our group, even trying to get into their room. We complained to the management and to the organiser of the MA group. The organiser said he couldn't do anything as the guy wasn't one of his MA guys, he was a 'friend' of one of them and not really part of the group. Also, although being the organiser, everyone had come 'on their own', so he couldn't tell anyone to leave. The management backed his position and did nothing.
We informed the organiser of the sailors' group and he said he was already aware of this man's 'interest' in young girls. Still the management did nothing. It was the last time we used that place!