All protective clothing needs to conform to certain safety standards to protect workers who are employed in a high risk or hazardous environment. Anyone who works on a public highway, in a high fire or flame risk situation, will need specialist clothing to keep them as safe as possible.
EN Standards can be very confusing, so you need to know what to look for. The term fire retardant as applied to organic (i.e. containing carbon) materials, might be better being referred to as reduced fire hazard, as all will burn under certain circumstances. First of all, if you need specialist work clothing or protective clothing for those at risk, you need to go to look very carefully at what you are buying and who you are buying it from. Flame retardant clothing is a pretty niche market and you need to buy from someone who knows what they are talking about.
You will see all sorts of symbols and codes written on labels, so which is correct? Well, the answer to that is that a lot of them may be correct as standards have changed. This does not mean that the old standard was incorrect, it simply means that the new standards will make clothing even safer.