Yes.... people who serve food to Vegans, should know what the word Vegan means.
Eating out is one of the worst experiences a Vegan can have, not only the difficulty, but the social exclusion and being the 'complication' among a group of people. Often makes an arduous time out of something that is apparently done for enjoyment and stress relief.
If more businesses and companies were well informed as to the standards of Veganism, not merely that they are statistically "missing out on a piece of the Vegan pie (ethical market)"... this would make for a better cultural experience. Much of which our Australian society lacks, beyond exposure to multi-culturalism. Indian food for Vegetarian standards, etcetera.
Asian for... every creature from the ocean. Obviously because the diversity has been out of reach, thus it has survived till now. It is most concerning going into a non-english fluent establishment and not knowing if they are just being polite, or actually have someothing you can ethically eat, let alone whether it is good food, made well and worth the wait.
Your apsolutely right, it is important not just for us but also by simply mentioning vegan to someone can sometime result in it 'clicking' so to speak so is in its self a form of activisium

not just to the employee or owners of companies you ask but also if they do get in on the action they also end up advertising on websites, social media and billboard ect so when people see this it makes them educate them selves as to what a vegan is...
But it is getting better, curtain things in the media have actually helped where some people actually assumed it would be damaging to the cause; evidence shows that the number of vegans rose since the Morrissey and Russel Brand's discussion just by raising the question even though people assumed that due to his approach and deliverance of information and opinion that people would close off... There was also the whole Beyonce thing was good for our numbers... With it getting many young girls (her fans) and dieters asking what a green diet is for their weight loss endeavors.
But yes it most certainly should be compulsory to inform employees as now it is almost like working in a fruit shop but not knowing what a lychee is...

so yes if in the food industry you must be knowledgable... Same as if you have an admin job it's compulsory to know how to use a printer
But at the same time I think we all need to not be aggressive towards people that have no idea what a vegan is because none of us want to be bully's do we... Remember you can't blame someone for not knowing something and getting annoyed about each time you encounter another person that doesn't know; rather see it as an opportunity to inform and convert them...