In Poland it actually is a race to the bottom: there are 4 different mobile operators and every time one of them announce a new offer it usually is cheaper than anything already on the market. And within few weeks other 3 usually follow with similar price cuts.

EU's roaming regulation is the latest example: 3 operators announced tariffs that pretended to make roaming free, but have multiple strings attached. But the fourth one, Orange, announced offer without any fine print, just equating roaming prices with domestic ones, thus forcing other three to do the same.

If I recall correctly there wasn't a single price raise in Poland in the last 15 years.