Why don't we know Buddha's exact birthday?

How come we don’t know the Buddha’s actual birthday? Don’t get me wrong I love celebrating the Buddha’s birthday a couple times a year, but it amazes me we don’t actually know the day.

I think it says a lot about the original Buddhist texts. As they were initially memorized and passed down orally, it shows the fickle nature of memory. I know it’s not really important, but it is something worth pondering. In the Buddha’s time there must have been huge celebrations and for many people a day they held very closely. To the monks of time, but also in the broader lay population. It is amazing how quickly beloved times of Buddhist history fade. In relation to the duration of time since the Buddha was born and how far away we are from the birth of Maitreya, it is something lost so early.

I do believe in my heart that the real flame that last is the Dhamma, and as the flame slowly fades, the least important things fade. So the birthday isn’t really all that important, but as I said it is something interesting to acknowledge.