in THIS part. trip it is because its partly on the newly opened HS Milano-east toward Venezia route. That also explains why its cheaper as just on the older route from Milano.
Compared to the continent, ATOC-1st, at least on the really very, very expensive bisnis-cl type fares+Service fro/to LONdon also includes food on the train. Thats very uncommon for the classic national railroads.
IF booked smartly on advance, both bahn=DB and CZ Rail=CD also offer quite low fares and CD even on connections into Germany, both lower and much more available as on bahn.
Tipically PKP and PR in POland offer ''competitive'' fares where there is strong competition from buses or whatever other operator (f.e. Krakow-Katowice, bus is both much quicker and much more often as trains-these suffer from bad tracks due to subsoil bad from mining underneath).
ITaly has a tradition since Mussolini of very low local fares and not that long ago there were just these-for any train. Since the split off of long-distance and regional controlled local trains, those for long-dist. have gradually risen, but the gap with other countries remains.