Yes Middle Class in the USA means more of the average family and it used to mean of a certain modest but secure financial status, so yes, more akin to a working class/upper working class in the UK. When I moved to the USA initially over 25 yrs ago most people in the US considered themselves Middle Class while most people in the UK would have called themselves Working Class. While “MC” in the UK was most definitely NOT considered the Average Joe and most MC would have been offended by the suggestion, as it was associated with professional white collar jobs and larger homes in well to do areas; Average Joe and Middle Class have very different connotations in the USA and mean something different. They mean the average family, who are solid citizens, modest but respected and the backbone of the nation. A solid factory job which paid the bills and meant a family in a small town could buy their own home were most definitely MC in the USA, while in the UK, the job, location and neighborhood would have pegged them as culturally WC/UWC.
Unfortunately the economic policies that have affected the average worker everywhere in the West which focused on Globalism and moving manufacturing to China, have had a very detrimental affect on the USA Middle Class. There has been a hollowing out and what had been modestly prosperous small towns which have fallen into poverty or are definitely struggling much more than they were 30+ years ago.
Just like in the UK, those with access to good higher education, skills and knowledge economy jobs have moved up the social ladder (at least, until recently) and the already wealthy have become EXTREMELY wealthy. As the USA is still the biggest economy in the world, if you are at the top of the tree here and were investing you couldn’t have failed to make a killing. UMC here is now very lavish, while much of the “Middle Class” has sunk lower into the more insecure working class. The Middle Class has shrunk and now to maintain a modest but comfortable standard of living it can cost a great deal more just to hold your place in the social structure, especially in the large coastal cities, where the “Middle Class” would be wealthy in other parts of the nation.
The huge economic changes explain a lot of the extreme political changes, along with the rise of the internet and social media.
Average wages have stagnated since the ‘70s while the net wealth at the top (UMC and above) has exploded. People are now living completely different lives from others in other parts of the nation (or within their state) in many areas and don’t appreciate they are in a bubble. So while the upper classes obsess about Identity Politics, many in what was the MC are barely hanging on, and just like in the UK are in debt. Often not because they are crazy consumers but because they got a medical bill when they were not insured or were not covered, or divorced and had to maintain two households.
Although, it’s still possible, if you pick up strong trade skills (plumbing, electrician) or a decent degree you can move into some of the smaller big cities and still afford a modest house. Again, the housing stock where the jobs are is low, just as in the UK. Many families that in the past would have sent kids to the local state/public college can no longer afford to do so and have to be ready to take on debt. It often seems to me that the UK has taken on the worse US policies (like paying for college) that have impoverished the generations under 45.
I think there is a very careful avoidance by the MSM and multinationals to talk about class and economic disparity, that’s why it seems they have gone full-on embracing all the latest Identity Politics groups (transgender etc) because it means they don’t actually have to change anything and takes the heat and attention away from them.
This started particularly after the Economic Crash of 2008 when the Occupy Wall Street Movement actually scared the crap out of the multinationals on Wall Street, they wanted to quickly move the narrative and focus away from their destructive economic policies and greed and focus on topics a lot more unthreatening to them and superficial economically. You can be sure that if Wall St is supporting your movement and ideology it won’t change anything for the better for ordinary people, especially women.