If you use String for all your data types than you are no better than a dynamic language. There are many string like things that benefit from their own types, e.g. currency, identifiers, post codes. Such types should only be created from a parse of valid strings, i.e. no empty strings, whitespace, illegal values etc. They do not have to be Alan Kay "objects", despite what your language or thought leadership is telling you. They should be values with value-based equality. A modern statically typed language should let you define such a type in a few lines. This is all done in order to make illegal states unrepresentable, which is what type systems are for.