It's called transaction re-ordering. The bank claims the that large transactions (like rent, mortgage, etc) are likely to be the most important and that you, the customer, would want those to be processed first. But, the math works out in favor of the bank because you get more fees (exactly as you showed in your example).

I remember this being in the news several years ago. I don't remember if anything came of it, maybe somebody else here does. But, personally I did opt out of all overdraft services from my bank - so if I did run out of money my charge would simply be denied. As far as I know this never results in any penalty. Any automated billing I have set up seems to be fault-tolerant and will just notify me to verify my card information and re-try the charge a few days later.