Probably because it's not an M1A, it's a BM59, which was the Italians deciding to not bother with all the expensive refinements the US was slowly working on with the M14, and instead just adapting their M1 Garand clones into select-fire 7.62mm NATO rifles taking box magazines. Not as refined as the M14 but it was ready many years before and for a fraction of the cost (the receiver is 99% the same as on an M1, and many other parts interchange). The Italians also had the good sense to put a good compensator on a select-fire battle rifle with a dropped stock, a feature I think the M14 would have greatly benefited from.
I'd like to imagine that surviving Italian WW2 veterans were part of what lead to postwar Italy adopting the M1 as their rifle. Picture some dude who was previously issued a Carcano and the typical diceroll ammo Italy was producing under Mussolini, and who had to face American soldiers who typically had a slick and fast automatic with ammo which actually adhered to a spec.
Now it's time to rebuild and to make sure the Communists don't just waltz in, and they're gonna need some better guns. What's a rifle they know for a fact is good and which they could have available on pretty short notice? That American one. Could they then catch up with the new NATO meta by just adapting the Grand Padano Pinger? Turns out, yes!
No clue how well made an Indonesian BM59 clone will be, but I'm excited at the prospect of more common and less expensive ones.