What's the cost of a high visibility vest (BTW, is there a nickname to it)? You can buy one one for a dollar, I presume, so there is no reason for an employer not to hand one out to their employees. I go through a HVA every three months or so.
We are mandated to wear them every time we set a foot on the tracks. Every time. If we fail to do so, we're in for tea and biscuits and, if something happens, for some legal action. There have been cases of colleagues not wearing a HVA while moving around on some slow speed tracks - maybe shooting a picture of their train - and an engineer passing by called the signalbox and reported unauthorized persons on the track . Which leads to the Federal Police coming into action and a Befehl for the next hour for every train (dozens of them) passing by to proceed on sight. This is why I wear them unless I feel absolutely stupid doing so, which is quite often, I admit. Uncoupling two locomotives in the middle of a switching yard - I'd say you'd not be doing this if you wouldn't belong there and wouldn't know what you're doing, so you have to be a railroader and not some looney running around just because of the matter of fact.
On the other hand, it is quite a relief if you see some orange and bright ahead of you in the middle of the night. You won't panick because you see the guy in front of you for several hundred foot instead of inches.
"Railways are not intended to generate a profit, but to be a beneficial institution for the public." - Otto von Bismarck