Can a company fire you for having a preventable accident?
Sure, but it’s unlikely they would unless the company perceives the driver as too risky to bother retraining. If the company policy outlines dictate that termination will result from a preventable first offence, then you’re out the door. Presumably, you read the policy and procedures manual before you signed on, so this shouldn’t come as a surprise.
On the other hand, perhaps you’ve demonstrated certain attitudes that the company finds undesirable. In having a preventable accident, you’ve just handed them an opportunity to can you for no other reason.
Frankly though, the company would have to document their reasons for firing you, including previous warnings and past performance records. If you’re a difficult driver, then they might have a case. If they just don’t like you, then you may have a case against them for unjust dismissal.
It all depends on the company’s policies. It’s up to you to find the fault in their firing you and bring it to the attention of a good labor lawyer. But be realistic, if you haven’t lived up to expectations don’t bother hiring a lawyer. Just get a new job.