Chances are what you notice about their pool is it is well balanced, this may be on purpose or may be an accident, it is certianly possible to do this without a UV sanitation system, it is also possible to have an out of balance pool with UV sanitation. The thing about UV systems is they can only treat the water that passes through them, not the stuff that may be growing in your pool and clinging to the sides, under the ladders, etc. to kill those things and to keep them from growing in the first place you need chlorine in the water. The simple reality of the sitution is most outdoor pools get more than enough UV from sunlight to reduce the CC products if they are properly balanced, having a UV system may extend the comfort zone of this balanced range a little, and if you have money to burn there is no harm in it.
Ike
p.s. Keep in mind "that chlorine smell" that most people complain about around pools is really combine chlorine products, which is often a sign of a pool with too little chlorine in it, not too much, a simple example of this, is go open a bottle of unscented chlorine bleach, carefully smell it, you will not smell much chlorine smell, in fact the bit you do smell is likely causes by the chlorine reacting in your nasal passages forming those dreaded combined chlorine products (this is the same as when you get bleach on your hands, etc.).