[telesilla]

Isn't this the same in Mexico and other central american countries? I don't know what they don't use vosotros there but perhaps it's a link to the reason in your home town. Ustedes is very normal in Mexico and use of vosotros indicates you are a foreigner (a native speaker should confirm but that's my experience)

[narag]

Not sure if I explained it well. The difference between tú/vosotros y usted/ustedes is the former is informal while the latter is more formal, showing extra respect for the interlocutor. Usted/ustedes uses the same verbal forms as he/she/they, instead of the ones for "you".

The oddity is that this use of "ustedes" (only in plural, not for "usted") uses the verbal form for "you all" instead of the verbal form for "they", so it's weird for people from other parts of the country.

As for the use of "usted" in general, it's declining, specially in urban areas.