Is the Fischer Esterification mechanism very simplified? Example mechanism:

Is that very simplified, or is that pretty much what is very likely happening at the molecular/atomic level when you do the reaction in real life?  (Of course besides the free $\ce{H+}$, that is obviously hydronium, protonated alcohols, or the acid itself.)
That is the wrong question to ask. Mechanisms are putative pathways. Accepted mechanisms are mechanisms that we have not found evidence to refute. There is no way to determine whether a mechanism is the true mechanism.