If Amy Pond's village is too small to have more than one post office how can there be enough demand to sustain a Kissogram business

Amy Pond lives in that village. She could work somewhere else - you know, like going to towns and cities and kissing people there. She mentioned that Gloucester was a half-hour drive away.

Besides, if she worked only in that village, old ladies would know what her job is, and they don't.

Even though she doesn't have a car...

Also, she is probably freelance and may have another job altogether.