While this will certainly apply to RTR model trains, I think you are overstating the problem with regard to the more specialised items like kits, detailing items and models that are expressly not intended for children.
With reference to the
Council Directive 88/378/EEC of 3 May 1988 on the approximation of the laws of the Member States concerning the safety of toys
it states under ANNEX I:
"PRODUCTS NOT REGARDED AS TOYS FOR THE PURPOSE OF THIS DIRECTIVE
(Article 1 (1))
1. Christmas decorations
2. Detailed scale models for adult collectors
3. etc."
As I think it has already been mentioned here, a supplier only has to print "Not for children under 14 years of age", or words to that effect, and the problem is solved.
David