Motivation has nothing to do with it. The development of power and influence through asymmetric growth in the industry is enough for this to emerge. There are still small banks today, but it's no coincidence that the largest (and thus overall best performing) banks cheat the system. The best performing become large and powerful on their own.
Capital is more than just money. It takes a lot to jump through the regulatory hoops, money requirements, and insurance costs while having competitive prices against other Banks and still make a profit.
Even if it was just a money issue, new banks do still require a fair amount of money for relatively little profit in an industry that is well established. If someone is going to put their capital on the line, why wouldn't they put it in a higher growth industry?
These don't make new bank creation impossible, just unlikely.
"It takes a lot to jump through the regulatory hoops, money requirements, and insurance costs while having competitive prices against other Banks and still make a profit."
And yet you still blame capitalism?
It happens. My parent's neighbor was involved in starting up a new small local bank a few years ago. Now they have three branches.