I'm just wondering why Stata gives CIs for binary variables - ci proportions varname - but, as far as I tried to find, we cannot have results for categorical variables.

Code:
. sysuse auto
(1978 Automobile Data)

. ci proportions foreign

                                                         -- Binomial Exact --
    Variable |        Obs  Proportion    Std. Err.       [95% Conf. Interval]
-------------+---------------------------------------------------------------
     foreign |         74    .2972973    .0531331         .196584    .4148353

. ci proportions rep78
no binary (0/1) variables found; nothing to compute
Am I missing something, is it technically impossible or we just don't have a user-written program to estimate these proportions with CIs in Stata?

If it can be done, and considering (and maybe I'm wrong) we don't have it so far, maybe this thread could foster somebody to create, say, a SSC (or SJ) - tabci - ado file.