The laws have been slightly firmed up around this now. Traders aren’t legally obliged to fulfil an obviously incorrectly priced order (like a brand new product at a tenth of the price) just because an automated system has accepted a purchase request.
It’s not so much as the law has changed, just how traders impliment their sales process and the associated case law.
Basically rather than accepting your order they say “thanks for your order” and only accept it when they take the money.
Once they take the money it’s yours.
Big online sellers have software which flags unusual activity on a product such as if a pricing error goes viral so they can then reject the orders before they have accepted them.
A small LBS may not be aware of this nuance so you may have just saved them £1,800.