I just passed through security at the Xi'an airport (in northwest China) and was surprised to have my belongings searched by a young woman on whose snazzy black uniform, instead of an ID number as a regular worker would have, there was a label that said only SHIXI ("in training; practice"), with no trace of the corresponding characters 实习 anywhere about her. When I read out the pinyin with correct pronunciation and indicated that I knew immediately and exactly what it meant, the young woman and her co-workers were obviously pleased that I could do so.
Even more thought provoking is the fact that many Chinese police cars and uniforms have written on them GONGAN ("public security") rather than "police", and sometimes not even 公安.
When I encounter such situations, I often wonder:
1. why they choose to use pinyin and NOT Chinese characters
2. why they choose to use Mandarin in pinyin instead of English
3. for whom the sign is intended
These are actually very important questions, because not using Chinese characters or English is making some kind of statement (whether consciously or subconsciously) through the choice of script and language: it is Mandarin, but it is in pinyin, not characters. For some reason — and in a very public and vital setting — pinyin is chosen over English and often even over characters.
I think I know the answers to the above three questions, but will refrain from stating them until hearing what others have to say.
Perhaps we may take this open use of pinyin as evidence of an incipient digraphia, in which pinyin and characters coexist, but are used in different realms and for different purposes.
Will practice make perfect for pinyin?
[A tip of the hat to David Moser]