Wrapping routines (and variables too) in "static" classes, is a very good practice. It is a way to force qualifying function calls (and variables).
A very (c++/java)ish view
Please avoid using this argument.
which was formed exactly because a lack of "interface/implementation" division.
Of course not. When you create a function intended to be used by other units, you have to declare it in interface section, don't you?
Then your options are:
1. give it a long and cryptic name and hope that it won't clash with some other identifier.
2. write a comment above the declaration to ask users not to forget to prefix it with unit name, or to think well about order of units listed in uses section.
3. put it in a class, let it be a class static method -- now you do get help from the compiler, which won't allow using your function without prefixing it with class name.
Choose according to your personal preferences.