In this interesting post about Italian food, one man writing about Italian cuisine in the 1800s said he went from eating meat three times a year to three times a day when he moved to the US.
Did immigrants adopt more meat in their diet because they could suddenly afford it, because of pressure from the dominant American Cuisine which was already in place, or something else? If it was all about affordability, why did the US have cheap meat compared to other countries?
Wow this question is perfect for me since I wrote a whole book about this. On my phone so I can elaborate in the morning but for now I’ll summarise...
Basically cheap meat (particularly beef if we are talking 19th century) was about land and distribution. Beef can be produced cheaply but to do so is very land intensive so you need a way to get it quickly to people in distant places (and people really prefer fresh, not salted beef!). So for that you need refrigeration and a pretty good rail network. But you also need things like a cheap labor pool (the very immigrants you mention in your post) and all sorts of business strategies to maximise distribution speed. Four firms headquartered in Chicago, most famously armour & company and swift & company figured this out in 1880s.
But there’s a final piece of the puzzle. You need a society that accepts you can slaughter things in one place and consume their flesh a thousand miles away. That seems normal today but was really weird to people back in the day. Basically, it took marketing, low prices, and even court regulatory rulings to make that happen. Key court case is Minnesota v barber. It also took public faith in sanitary meat which was really shaken w publication of the book The Jungle and only restored in 1906 with the federal meat inspection act and the FDA.
Regarding the comparisons w Europe the key differences are a HUGE amount of grazing land and the emergence of a production system that was dominated by meatpackers who could push low prices over everything else. In 19th c Europe there are all sorts of powerful interests (you could view those as either bad or good) who would fight against that.
To summarise, the key is land, efficient slaughter, and a means of rapid distribution. How all those things came together in the US was a combination of technology, human exploitation, circumstance, business genius, and government policy.
Lastly, as you imply, the key thing about meat in America wasn’t that Americans just happened to love meat, it was that for people in the US, their special occasion food (meat) became all the time food during the last half of the 19th century.