If there was a company handbook, the bonus structure should be outlined in that. If the other companies were small mom and pop, they may not have known to do this. Any regular sized or big company especially with an HR department would be able to point you to the bonus structure.
Employees need to be fully informed about their rights and privileges, including their compensation and benefits, and that includes the potential rewards (bonuses) that they can get. This will inform them in advance what they have to do to earn these rewards or bonuses.
If you left the company and were expecting a bonus (for whatever reason [like maybe u got one last year]) and the company decided not to give u one, and u sued that company, then the company would have to prove exactly how they give out bonuses (in the past) AND prove that you knew exactly how to get a bonus.
(Think of a racial lawsuit in which one person sues because they didnt get a bonus but another did and there was no outline on how to exactly get a bonus, and it should be clear the importance of outlining to all employees how you get a bonus)
A company cannot charge you for damage to or the loss of tools. Therefore they cannot negate your bonus (wages) because u broke something or lost something UNLESS it was proven u were negligent. Even then, still need ur consent.
Moreover, if the pay/bonus structure changes, employers must inform employees.