"TiVo arrived in the UK in 2000, so some 15-year-olds have never known TV without instant choice"
Not just that ... we got a TiVo 10 years ago when our sons were 1 and 5 so indeed grew up with this as "normal". Certainly had problems when visiting other houses etc where they (especially younger one) were unable to comprehend at times that we couldn't just press pause or record so they could continue watching later when we were about to have a meal etc!
"but the inability to understand the attraction of channel surfing was almost certainly what caused it (and its contemporaries) to fail when launched on this side of the pond"
the primary reason why TiVo failed on "this side of the pond" was that they handed over the responsibility of advertising it and handling customers to Sky not realizing that Sky had a (much inferior) competitor that they would launch 6 months later. The initial TiVo advertising was woeful and didn't stand a chance as soon as Sky+ was ready since Sky plastered continuous Sky+ demos/ads onto all its channels when no programs were being shown. Reason I went for TiVo was that I'd been working in the US around the time it was launched there and had at the time thought it looked great and only didn't get one since we were about to return to the UK.
Suppose there's a slight learning curve in getting used to a TiVo world but seriously apart from "live" programs (news and sports) we rarely watch anything "as broadcast". And with children having a season pass to ensure that every day there are new episodes of teletubbies/balamory/scooby-doo/ben-10 or now QI ready to watch is great.
Looking forward to my new VM TiVo arriving in 7 days time!