is someone paying someone to makeout with someone a form of prostitution (in kid world)?

That depends on some definitions.

For example, in the dictionary "prostitution" is defined as: "the act or practice of engaging in sexual intercourse for money."  Is kissing a form of sexual intercourse?  Maybe, depending on your personal opinion.

In legal terms, "prostitution" is defined differently:  "Prostitution laws make it a crime to offer, agree to, or engage in a sexual act for compensation."  Is kissing a sexual act?  Most states would say "yes".  (If you can get in trouble for "sexual harassment" for kissing - that would make kissing also eligible as a sexual act for prostitution)