Any student can submit a competing offer and hope for some match. It’s an accommodation, when the college feels like it, for various reasons. A reconsideration of the financial facts presented and run through their formulas. Follows policy. Not some throwing money at Billy or Susie to get them on the team.
It may function, on some basic level, as incentive (“OK, Yale is my first choice and they matched (or came closer to) H’s aid. Now I’ll go to Yale.”
But it’s not a bribe. Not something underhanded.