Unless you're paying EU100 per litre, your "balsamic vinaigrette" isn't made with proper balsamic vinegar. It's made from regular vinegar mixed with colouring agents, flavouring agents and preservatives.
Proper balsamic vinegar is made using a solera system, and takes a number of years. I doubt any restaurant chef would use real balsamic vinegar to make a "balsamic vinaigrette"; the real thing is for sipping.
I'm not really being fair. It's just that the standards are terribly confusing. There are two main standards; one is ultra-strict, and the other is so relaxed as to be meaningless.
Well, that's how I see it. I didn't mean that the lower-grade stuff is 'knock-off'; I've never so much as seen a bottle of the 'proper' stuff, except in photos. But I'm sure I wouldn't take snifters of normal deli balsamic vinegar.
Proper balsamic vinegar is made using a solera system, and takes a number of years. I doubt any restaurant chef would use real balsamic vinegar to make a "balsamic vinaigrette"; the real thing is for sipping.