Many European countries have not yet issued any statements on this topic. In Germany specifically, this topic is uniformly regulated for the whole of the Federal Republic by the DGUV paper (German Social Accident Insurance).
This paper refers to Appendix B, EN 469:2005, which regulates the minimum quantity and positioning of reflective stripes. This DGUV paper specifies that persons are exempted from wearing warning vests in secured accident areas.
Other countries are already taking this topic into consideration, further developments are to be expected.