Certainly it's very common, but certainly not "every" residential building has one.

Just fyi, Dublin has a rather dense core (too dense) surrounded by a 10km wide ring of extremely low density suburbs where services can't function efficiently. Everyone has to drive a car. It's a Detroit model disaster.

Whereas Amsterdam is a uniform medium density throughout and at its border it just ends and gives way to farmland. It has the right density throughout for services like transport, hospitals, schools, recreation, shops etc. to work.

Looking at London, the top rated place is Soho. Sure, a lot of people do choose to live there, but when I moved to London, I'm so glad I had to walk across central London on a couple of occasions before I actually found a flat. I went through Soho once on a Friday night and realised there was absolutely no way I'd ever be able to sleep at night and ruled it out. The next highest place is Seven Dials, which is fine for a night out, but again I wouldn't actually want to live there.

I actually chose to live about a minute walk from Hyde Park and 5 minutes from Paddington. That scores 89, so not much below the 96-ish of those top 2, but it's around 30-45 minutes walk from both of those. I think it only scores so highly because of the food options on Edgware Road, but there's not much else to do in that area, certainly not within 10 minutes walk, and I would frequently walk into more central London to do things. My cut-off before using the tube was 60-90 minutes walk each way depending on my mood, and would only use the tube on about 10% of days and averaged probably 90 minutes total walking on normal days. I guess my idea of walking distance is much higher than the 10 minutes suggested by the article. I'd definitely choose to live there again though if I went back to London.

EDIT: I've just looked at where I live now (a long way outside London). My current place scores 38 with only 1 in nightlife (a pub) and zero in all the other categories. Ironically, it gets the same score of 38 as an adjacent tile which somehow gets 0 in all the categories even though it's closer to the pub. Another adjacent tile scores 18 with basically the same stats, seemingly losing because it has fewer marked parking spots and no park (even though that tile is on a massive area of common land, hence why it doesn't have many facilities). The centre of the town, all the tiles score 96, which is true there are more things to do, but there's very few nice places to live in any of them. The whole thing seems a little odd to me, and I certainly wouldn't use this to decide where to live.

| Most Londoners socialize in their own neighborhood and rarely cross the river -- pick your area carefully because it becomes your whole world.

This just flat out isn't true and is a bit of a historic trope

| Council tax varies wildly by borough, so two flats at the same rent can cost hundreds different per year in total.

Council tax is defined by the value of the property, not by the rent

| The Overground and Elizabeth Line have completely changed which neighborhoods are convenient -- don't just look at Tube maps.

The tube maps show the Overground and Elizabeth Lines as well as all the other TFL managed services. A better map of where is "convenient" is this https://neilgarratt.com/campaigns/improving-travel-times/

Having said that I 100% agree with the rest:

| Sunday in London is genuinely excellent with markets, roasts in pubs, and park life -- it's the city's secret best day.

| Cycling has become a serious commuting option with protected lanes expanding every year, especially south of the river.