Some observations.
1. I don't know if the map function is the same for everyone or whether my computer isn't compatible with it, but in London I'm sure the flags are randomly placed. They're all in places where it's expensive to live or are central shopping or business areas. The areas where I know the vast majority of the population lives (areas of dense housing in eg. zone 2) have no-one marked.
2. I fixed on one person and every time I re-loaded the map she moved to a different place (in roughly the same 1-mile area, but in London that's a million people). So don't assume we all live on the same street just because of the flags!
3. Although there are a lot of us from FF who live in the London area, that IS because there are 8.3 million people in London (or 15 million if you look at the metropolitan area). It doesn't mean we can all drop in to the same coffee bar though. It would take 1-2 hours to get from say where Softgirl lives to say where Debz lives, or from where I live to say where JulesTeak lives*. London is huge. So if you live in the US and are 80 miles from someone and have use of a car, it's probably the same journey time (ish). If only you all didn't drive so slowly, anyway
*that's not to say I've made that journey lol, before tongues start wagging haha
4. As Salt says, it's generally the same few people at all the meet ups. We ARE lucky to have them & each other but in all fairness the fact they happen at all is down to a hard core of people who work REALLY hard to organise get-togethers and to galvanise others into enthusiasm.