Convenience is the key word! 
If you buy them ready-made in packets, you just take it out of the
fridge, stick a straw in the tetra-pak or pour it out into a glass,
and enjoy! Later, just wash the glass.
Otherwise, you'll have to take the tin, open the tin, scoop the
milo, scoop some sugar, scoop condensed milk, boil hot water, pour
hot water, stir and stir, let it cool a bit, THEN you can drink it!
And then, after drinking it, you have to wash the cup, wash the
spoon, wipe the countertop.
Haiz!
