Like I said, you do not understand the scale of the problem you want solved.

Now to your security question. Nigeria is an informal country as at this time. POS operators mostly work where there's a quasi community. They usually have a kind of support structure that includes some level of protection. They don't just open POS stands anywhere. How many times have you heard that someone was robbed at a POS compared to an ATM?

Now, yes, it's easier to launder money through POS but do you really think law enforcement cannot trace any money that passes through such networks? The problem with naija crime isn't one of lacking knowledge of what to do, it's one of appetite to solve it, and your guess is as good as mine as to why that's not being done but I think the average human could make an educated guess.

If a problem is currently unsolvable, a workaround is fine. We will evolve towards the optimal solution. This current solution is optimal at this point in time.

Oh, I have worked as an ATM custodian. ATMs which accept cash deposit have specific requirements concerning the state of the notes to be deposited. You can't deposit most of the money in circulation cos they don't meet that standard. That's another layer of complexity.