Never had mine tracked or aligned unless I was having uneven tyre wear
....Obviously having uneven tyre wear would be a sure sign of either wrong tyre pressures or your wheels needing alignment. However, you'd be surprised how a car like the GTI goes off track/alignment simply due to being driven on typical UK roads. Unless you drive like a granny of course, but then you'd probably hit a few kerbs and so also need alignment.
Not quite true. Suspension and steering geometry will ONLY go out of alignment via two fundamentally separate ways. Either impact damage or the like has physically bent or deformed a suspension component - in that case, the damaged item needs replacing, before any re-alignment is carried out. Or, general "wear and tear" in the suspension bushes and swivels will cause a gradual change in alignment - which can simply be sorted by re-alignment, providing said wear is not great enough to lead to physical play or slop, which would be an MoT failure.
If you want to look after your car well and help your tyres last longer, have it aligned/tracked professionally on a VAG Beissbarth. If you don't care about such things, it's up to you. 
But if the tyres are wearing spot on evenly, it is a very good sign that the alignment is spot on.
I remember a thread on this forum about a year back, with a picture of the rear tyres, and the poster concerned his alignment was out, because the outer section of the tyre didn't seem to be touching the ground. We told him that it was caused by the rear wheel camber, and that when cornering, the forces would "even out" the wear across the entire tread width.
