Mayonnaise is a dressing made of eggs, oil, and vinegar -- if it's not made of those three ingredients, then it's not mayonnaise and shouldn't be marketed as such. Too much label substitution is permitted in the US food industry already.
Most people don't eat mayonnaise so that they get their daily recommended allowance of vinegar.
What exactly are you afraid will happen? Someone will die because they didn't eat something with eggs in them?
If someone cares that much about the ingredients they should read the ingredients list, or see on the front where it says "egg free."
Ideally, the relationship between the name of a food product and its ingredients should be one-to-one. It's a way of enforcing pure food labeling by producers with respect to consumers.
If a product labels itself mayonnaise, then customers should know what its general ingredients are immediately. Even in the US, perhaps thanks to the egg board, "mayonnaise" is not yet a generic trade label for any shelf-stable edible white(ish) emulsion. In which case it can be called a "sandwich spread" or some other more loosely defined term.
