Result of lack of standardisation

Problem resulting because of lack of standardisation -

After a dinner in a restaurant, as I went to the washroom I saw one tap opened and water flowing unnecessarily. I closed it, and then thought how would it happen that s'one would just leave the tap on, and walk out..

There can be only two possibilities -

1. Water stopped as she was washing hands - which was not the case, as this was a well maintained place ... Then

2. Lack of standardisation, while she assumes, in hurry, that it's a press kind of / with sensors tap and would be off automatically, and just walks out ... Which leads to the wastage of water that I witnessed ...