Yes milk does spoil faster when in plastic containers than it does in glass containers or Jars.
Milk that is put in glass jars or containers last longer and doesn't spoil as fast as it does in plastic jugs.
For some reason milk seems to taste better when it's in glass jars or glass containers than it does in plastic.
The plastic probably leeches some chemical into the milk which probably alters the taste some.
Plastic jugs for milk are much cheaper to make and transport and are lighter as well.
So by putting milk in plastic jugs it makes the milk bottling process cheaper which makes the milk cheaper for us to buy.
You can buy milk in some stores that comes in glass jars and it's what I buy because it tastes better to me.
I found that the milk lasts longer in the glass containers than it does in the plastic containers.