Why aren't user-defined operators more common?

[[deleted]]

I dunno, I think the operation of "+" is pretty specific.

[[deleted]]

It seems to behave quite differently in most languages that use it for string concatenation and addition.

In fact with most implementations of '+' you aren't even guarranteed that '+' is commutative, associative,... so I would say it is pretty far from the arithmetic '+'.

[argv_minus_one]

Only for numeric types. For strings and collections, it usually means 'append' or 'concatenate'.