Belgium is only as large as Italy's Lombardy plus Piedmont, two adjacent regions in the north west. There is no Italian equivalent of a two region pass, but Lombardy has an unlimited monthly pass for all public transportation, bus, metro, regional trains, at 107 Euro, plus an extra 40 Euro to access fast national trains (within Lombardy). Given that an unlimited monthly city pass in Milan is 35 Euro, it's about the same cost of your Belgium ticket. It's for half the area but it's unlimited. Anyway, if we had a region the size of Belgium probably the price wouldn't increase much: people tend to travel close to home.