quite right the ratio of tenors to altos in a band is higher.

the only 2 reasons i can think of are –

probably being sexist – ladies find a deeper voice more attractive – so the Tenor wins

if two guys stand on a stage and
one guy takes out a tiny sax (alto) and another guy takes out
a whopping big sax (tenor) – who do you think will be noticed the
most?

perhaps the tenor blends in better with the base player for back ground fill, then for spotlighting
the tenor can draw attention to itself in the intervals by screaming altissimo?

Where as the alto being mid range – is stuck for playing higher up?