Glad you threw in "modern". We do have regional food cultures but they're too boring for most people, especially if you do it right and shift the menu with the season ("Stew and cornbread? Again?" well yes, it's Winter, want a side of hardy greens to go with it? "ew, catfish! Gross!" yes, that's... what's around. What, you want mahi mahi?).
We want more variety and to eat all kinds of produce year-round. You can just pick any "ethnic" cuisine (especially if it has a similar climate to the one you're in) and get like results, but people in the US don't do that either, mostly, probably for the same reasons: that they'd start to find it too dull, or would prefer not to eat so many of the dishes for one reason or another that they'd have to sub in others from other cuisines to make up for it.
When I first started cooking I mostly just baked or pan fried meat, microwaves or sautéed vegetables, and made slow cooker chili / other soups. Maybe that doesn’t fit most people’s definition of cooking but IMO there is nothing wrong with a dinner of (seasoned) baked chicken thighs with some microwaved frozen broccoli. It takes like 5 minutes of actual work too.
That's not say I NEVER eat out of course, just, I save a ton of money cooking at home.