What's the point of giving a price for a US power plug in GBP?

Well, I know it's a little rude of me to answer rhetorical questions, but here I go anyway.

Because the fixed price is in GBP, and the US dollar price will wobble
around a bit from day to day. So what your credit card eventually gets charged
may not bear much resemblance to a price quoted here if he were to quote
in dollars.

OK, to be fair, here is a rhetorical question from me to which you are welcome to annoy me with a response:

What's the point of quoting the UK's Gross Domestic Product in USD?