I’m not sure I’ve made this clear.
The point is that there is a current fashion for neuroscientists to measure brain activity and attempt to correlate these with thoughts and feelings. Some parts of the brain consistently display activity at the same time that a person has certain thoughts or feelings. This understandably leads many to conclude that the brain activity being observed actually causes the thoughts and feelings. The bus analogy is meant to illustrate that this deduction could false.
Because, just as the fact that queues at buses, and buses arriving, tend to coincide, doesn’t mean that queues actually cause buses to arrive, so it may not be the case that brain activity actually causes thoughts and feelings. There may be a deeper process at work here which accounts for the correlation of brain activity and thoughts that doesn’t necessitate one being caused by the other.
All that this is meant to show is that the conclusion that brain activity causes thoughts may be incorrect. It is not intended to prove that it is incorrect. Other stronger arguments can be adduced for that purpose.
Most importantly, there is no account offered by materialists to explain what a phrase such as “brain activity causes thoughts” actually means. How does it do that? Brain activity and thoughts are two different kinds of things. To say one causes the other is pretty incoherent as it stands. It’s not being flippant to point out that the phrase “brain activity causes thoughts” is like saying “this chocolate bar will turn into a Mozart symphony” or “ I’m going to turn Wednesday into a dancing pony”. I wouldn’t go so far as to say that “brain activity causes thoughts” is an impossible description of reality. But it is pretty weird as an “explanation” because it explains nothing.