If the danger is low, you would realistically be paid by how much people would make from the drops/local resources. If the danger is high, payment would be more like a subsidy for the weapons you used. If you can do the same job without several cases of bullets and grenades, you earned that paycheck. But by the same token, getting one reward using a relatively stupid strategy like non-magical crowbars would be like gambling in a casino. So if the chances are 100 times better than the casino, you'd get people willing to try and cash in just once. The real problem is the massive risk disparity if raw stats can make you invulnerable to low level mooks. That's what screws up the economy, and gradually forces everyone to level up anyway.
There is also price affected by demand and supply. If you flood the market with a particular monster then the price needs to drop. That it doesn't feels fake. It is the reason I hate Lord of the Oasis. The protagonist trades with a system instead of real people so prices are fixed.. No risk of buying substandard goods
Much of this storys have weak foundations so authors do make such mistakes, instead of doing proper research on those subjects.