Because of Remainer Theresa May, for starters. Remember her spats with Trump where she voiced her disapproval of his rejection of liberalism?
She’s an incompetent fool, agreed, but she is grabbing every trade deal, even with Fiji, to prove she should stay in power. If she got a trade offer from the USA that was palatable to the British public she would have taken it.
There isn’t any statement from the USA that they have offered any so far, which they could have