What kind of company has this kind of turnover, that 6 mos constitutes a frikkin' bonus?
It's very common for companies to pay incentive bonuses based on company results to every staff employee. The amount is usually a percentage of base salary, and is pro-rated for those employees who have been with the company for less than the full year.
A flat $2000 bonus sounds sort of fishy, unless it's a contractual payment to union drones, or a boiler room full of minimum wage earners who rarely last 6 months.