I think maybe they call it Mimosa because it looks like the sensitive
weed mimosa pigra (which is the pest - it has prickle thorns on it and
forms shrubs which line riverbanks and prevent livestock access to the
water). I live in Australia and they have just started a campaign
trying to get rid of it.

But this looks like a proper tree - it has large version of the
sensitive leaves on the weed version the week has little pink fluffy
flowers like the tree.

I don't know if they are related or not, I'm assuming Mimosa pigra is
the scientific name, and if it is, it's not even in the same genus as
your mimosa tree. Anyone else know?