Well, I thought this, but after almost typing a reply I looked it up and they sold more consoles, had a higher attach rate, all while the 360 had a 1 year head start. It was closer than other gens though, I agree, and of course the Wii sold more than MS and Sony by a huge margin.
VGChartz gives the 360 the higher attach rate, but not by much. Not sure whether this is more or less reliable than where you looked though..
I think the perception that the 360 sold better comes down to the influence of American gaming media in the UK. The 360 outsold the PS3 by ~20 million units stateside. That's a huge lead. And when you look at the biggest English-language gaming news sites, most of them are American.
What's interesting about regional figures is it highlights just how big a disaster the Xbox One has been. Take the US figures off, and the One has only sold ~17 million units. The sales drop in Europe from 360 to One is over 50%. And in Japan (where Xbox sales have never been strong, admittedly), the One is outsold by both the 360 and the original Xbox. "Other regions" also fell 50%, despite adding a bunch of new markets during the One's lifespan.
The extent to which Microsoft messed up with the Xbox One is quite incredible. But then it was developed and launched at a time when Microsoft seemed to jump from one disaster to the next. The latter years of Steve Ballmer's tenure as Microsoft CEO didn't exactly have many success stories

When you look back at the concept which was announced at E3 2013, and then look at the console as it is now, the shift has been huge.
It'll be interesting to see how much Series X can turn things around. All of the right ingredients are there; Xbox is now its own division, is run by people who actually seems to love gaming, and evidently (given all of the studio purchases they've made over the past five years) the department has some serious money to spend. I'm quite looking forward to seeing what is announced next month.