Why does this matter? Surely when people say “low voltage lighting” it's pretty clear that they mean “12V”, so what's the problem?
This is not some pedantic technical point along the lines of “it's not an earth, it's a cpc” or “bulbs are what you plant in the ground, what you mean is a lamp”. If you start getting involved in doing your own electrical work, and start learning about regulations etc you'll come across references to “Low voltage”, and it'll be no good you thinking that that means 12V.
The Building Regulations, for example, which are law in England and Wales, contain a section on electrical safety, Part P, and the legislation says
The requirements of this Part apply only to electrical installations that are intended to operate at low or extra-low voltage….
So if you don't realise that “low voltage” includes your mains supply of 230V, you might think that the law doesn't apply.