PEGI ratings are useless these days and will shift the responsibility and blame to the parents of these kids. Perhaps in cinemas they work some of the time but there is nothing stopping these kids from buying games that are rated 18+ from digital storefronts and purchasing said lootboxes.
I said it before, the only way you can get this resolved is to licence it and fine and prosecute those companies that breach those licence agreements. Once the CEO's of these companies start getting criminal records and huge losses on their spreadsheets then they will be inclined to resolve this problem. At the moment its lining their wallets.