Why there are no new symbols being created, like one for concatenation

As an example, plus(+) symbol is used in several programming languages for string concatenation, provoking some unexpected behaviors in some cases. One example that illustrates this is: 5 + 1 = 51, but 5 - 1 = 4 (my intention is not to discuss about whether this is right or wrong)

Why no one is creating and proposing new symbols to fix these inconsistencies? I have the impression that our keyboards got stuck decades ago and only new currency symbols made to the keyboards (like the Euro symbol)

Regards