Okay, I will try and break it down, it`s one of those things that is hard to explain, I used odds of 25/1 for arguments sake, i`ve never seen the reel strips of Cashapillar, right here we go, you have hit scatters on reels one and two disregard this for a second, what are the odds of hitting at least one scatter on reels 3-4-5?, reel 3 is roughly 15-1, reel 4 is 25-4 and 5 is roughly 19-2, if you sort these spins out to so they don`t coincide with each other as such, so I rounded them up to a number they can be equally divided by = 30, reel 3 will have landed twice, reel 4 = 5 times and reel 5 = 3 times which equals 10 scatters in 30 spins, so basically there is a scatter on one of these reels every 3 spins or so.
The odds of hitting 3 scatters reduces dramatically if you have hit scatters on reels 1-2, as you have 3 shots at hitting one, however, the odds increase if you have not Ie. you need reels 3-4-5, next time you play any slot that you know the reel strips of see how many times you miss the last 3 reels when you have scatters on reels 1 and 2.
The odds of hitting the 1st two scatters on Cashapillar are 246.48-1, the odds of hitting a third are reduced unless you set a specific reel for your 3rd scatter to land as you have 3 bites at the cherry, so imho the odds of hitting 3 scatters should be readjusted accordingly as to which reels the scatters have landed on, the odds of hitting scatters on reels 1-2-3 on Cashapillar are 3647.904/1, the odds of hitting 3 scatters after reels 1-2 scatters have landed are a whole lot less than the odds on hitting the 1st or last 3 scatters.
Basically the RNG should re-assess the chances of hitting 3 scatters as the scatters land accordingly, although this would be impossible as the RNG decides when 3 scatters should land and the reel strips follow suit, and not as is the case which entails your calculus above, over a few million spins this will pan out and the maths will tally up correctly, but, if the reel strips landed completely random and not as programmed to land after the RNG sends the relative data, then the odds of hitting 3 scatters would change drastically as to which reels they land on 1st and 2nd.
Next time you play Cashapillar take notes of how many times the 3rd scatter lands after reels 1 and 2 have landed, or even better, see how many times reels 3-4-5 scatters will land to make two scatters, as to how many times they land to make three, like I stated above the odds should greatly reduce of hitting 3 scatters after 1-2 have landed, they do not, this is down to the predetermined RNG calculus of the reel strips and how many spins it should take on average before they land, real random stuff doesn`t work like this, take 25 million people (or how many combinations the UK lotto generates) each having different numbers but all the possible combinations have been covered, all these people retain the same numbers every draw, after 25 million draws do you think every single person has won, or some have won several times?.
I really hope this makes sense lol.