Programming only needs to make things as explicit as necessary based on the developer's desires and the system's assumptions. Where more detail is necessary, the programmer can add more code. For example, there's no need to tell a browser explicit rules for how users should be able to interact with an input field, since that's the browser's default behavior; you only need to specify different behavior when you want it to differ from the default.
Likewise for English: one can use natural English to add as many details as necessary, depending on who you're talking to, e.g. "Make an outline around the input field, and color the outline #ff0000." You can then add, if necessary, "Make the corners of the outline rounded with a 5 pixel radius."
In this respect, complex applications can be fully specified in English; we usually call those documents "formal specifications." You can write it terse, non-natural language with consistent, defined terminology to save room (as most specs are), or colloquial (natural) language if you really want. I wouldn't recommend the latter, but it's definitely useful when presenting specs to a less technically informed audience.
