I was initially confused when I read it, but I think that ‘trader’ here must be the politically-correct word for ‘tradesman’ (someone engaged in a trade) rather than someone who trades (like a stockbroker).
It can also refer to those who will take on contracts (plumbing / landscaping / roofing / building work / etc) without any intention of fulfilling them, or charge exorbitant, inappropriate and unagreed prices.
It's in such common British use that a TV show named "Cowboy Traders" was aired in 2012.
But it's understandable why they haven't used that here, as an insulation installer would rarely be called a builder, just like an electrician or plumber would rarely be called a builder.
The term seems to lack gender-neutrality so Wikipedia prefers: https://en.wikipedia.org/wiki/Tradesperson
The trouble with "trader" is that it usually means something else, namely someone who trades. A tradesperson doesn't trade; they practise a trade (= craft/profession).
Ambiguous on a global scale? Maybe. Ambiguous when you're standing in a builders' merchant? Absolutely not.
Edit: and as another commenter pointed out, it's literally the government definition of someone running their own business - "sole trader".
> ‘Tradesman’, which in the north is used to denote a workman who has learned a trade, while in the south it is made to apply to a man who runs a business.
That was more than a hundred years ago and things may have moved on a bit since then, and in any case that sentence is quoted as an example rather than a claim by the editors of the dictionary, but perhaps despite my current place of residence I'm a northerner at heart?
https://www.trustatrader.com/trades
So no, I don't think that's a regional thing.
It's a really old, and well known, UK expression, and not an affectionate one.
Although 'Tradesman' (or tradeswoman) is the overwhelmingly correct term in the UK for those kind of jobs, whether the work they produce is good or bad.
Where the downvoted is wrong is saying it is somehow a PC term.
There is nothing politically correct or incorrect about it. It is just the standard term. Meanwhile in Australia they use 'Tradie' from what I understand.
"tradie" is the variant i encounter more often, though.