Most electric forklifts use lead acid batteries. These batteries are only warrantied for 1-2 years because they fail unpredictably after that time frame (hence why they get replaced on that time frame). They also take forever to charge and their performance and lifetime is highly dependent on temperature. Basically, they are a pain.

EV buses will not be using lead acid and will use longer life battery tech (e.g. Li-ion), so your reason #2 will not be as big of an issue.