With proper disclosure there may be some leeway, but I wouldn't just assume paying someone for a fake review is legal. UK advertising laws can be very strict in some cases (and rightfully so, in my opinion).
I don't know UK law, but at least in the US, there's a clear difference between "illegal" and "liable". There's a lot of stuff that's perfectly legal, but that I may be liable for.
IANAL. I understand that fake reviews are indeed against the law in the UK (Consumer Protection from Unfair Trading Regulations 2008, Business Protection from Misleading Marketing Regulations 2008, etc.)?
But perhaps it's viewed as too loosely defined or hard to enforce.
In context here, liable:
1) Liable for claims that the fake review makes, i.e. held to the same standards as any other marketing/claims you make about your product,
2) Liable if you mislead consumers by making them think it's a real review.
"You are liable, i.e. you are the entity that may break the law"
The Digital Markets Bill may affect this in 2024 (?) - Not sure whether it will be more focused on regulating 'platforms'.
You're right that paid reviews may be legal if they're clearly advertised as adverts, as opposed to framed as impartial reviews. But walking that line is fine, right, because people expect reviews to be impartial.
Regardless, the legal obligation[1] to transparently advertise this is on the firm, not (just) the bought reviewer. IIRC the Advertising Standards Authority recently had a case on a social media paid promotion, which reinforced this. Regardless, IMO the statute is quite clear the obligation is on the firm.
It's just always surprising when companies think that legality and morality are the same thing. Either they didn't expect to get caught, or they see nothing wrong with it, that latter being worse.
The majority of companies that gets punished by consumers these days seem to me to be those who think that just because something is legal, then it's without consequences.
The obligation is on the reviewer to highlight they've been paid for a review, otherwise they are illegally misleading their readers.
Whether that's moral is another thing.