Deploying Ubiquiti's APs in managed (as opposed to standalone) mode makes this easy; even iPhones will transparently be passed from one AP to the next. I agree, though, the OSX/iOS roaming preference tuning is a bit batshit; they also refuse to drop your house's Wifi as you're driving away and want to switch to LTE ASAP.
Commodity/consumer APs aren't designed for handoff.
Plus also 5GHz is more resilient than that. Even in a solid concrete new apartment building in London I'd see absolutely endless 5GHz networks.
I knew other countries had heavily walls but didn't make that connection.
I quite like our cardboard walls though, they are trivial to repair and upgrade, and they rarely get damaged in real life, except if a Real Tough Guy punches one.
The insanity of moving just to get better wifi reception aside, do you mean move to North America where houses are built out of cardboard and sticks? Most other countries build walls out of solid materials and 5 GHz isn't getting through more than maybe one of those.
As for spamming APs, I really wish it were that simple. Apple devices cling to their AP until speeds drop to the dialup days and other platforms aren't much better. How did we figure out GSM roaming in the 90s but WiFi roaming is still a disaster 30 years later?