72 million Brits, and Johnson & Starmer are the best you can come up with? As a pp said, this feels really familiar. Not sure why people think those who run for political office are the best of anything. That's never been how politics works.
Biden is a decent tactical move of being mostly US-centre (UK right - Dems are closer to Tories in policy with Republicans far beyond them). Yeah, not the best American, but he might be able to appeal to larger parts of the very disparate groups of the country than some of the other options (as much as I hated Yang and Tulsi's early losses, I understand why they happened). Not sure he's managed it so far, but he's very status quo, very safe, the Dems could use that if they can get past this idea that they can win on just not being Trump. Unless they can talk to the parts of the country they threw away last time with some consideration, they will lose again and they won't get the blame the smaller parties this time (though they'll probably try) as they're barely making a ripple. The US system requires that you consider all the regions of the country, not just where the Dems would like.
As for why the system can't be changed - it would require an amendment to the constitution. I don't think we could get 1/2 the states to agree to anything at the moment, let alone the 3/4ths that would be required. It's one of the issues of a written constitution compared to the UK's unwritten one, changes to it take a lot more effort.
And let's not forget that while many of the Dem candidate argued for the change to the Presidential voting system these last four years, when asked if the primary popular votes for their party should decide who runs, all the remaining candidates but Sanders said something to the tune of "there are procedures to follow", which is pretty much the same fucking thing - the electoral college is the procedure to follow. They only care about changing systems they can't think to work in their favour, and they haven't figured out how to win without ignoring the middle yet.
So, while a small part of me is tempted to leave it blank, I'll most likely vote Biden. Better for those back home to fight against for change than Trump, Jorgensen, or Hawkins.