A Google search literally takes seconds. I have no working knowledge of any currency but my own (the pound) but when the subject of money comes up with a person from outside of the UK and I am told that they spent $30 or 30€ or 30 whatevers, I just look it up.

True, but OP does know because they're an American. It's not the same as talking to a random person whose currency is different from yours. It's bizarre to be talking to your mum and expecting her to Google something that you mentioned instead of giving her that context yourself like in a normal conversation.

Expecting people to bend to your wishes because you're American is most definitely ridiculous.

Completely agree with this, though.