Man, I explained how.
Think of it this way. You're unemployed and collecting welfare, $400 a month, enough to survive at a very basic level. Now you get offered a job that pays 8,000 a year, it involves you working full time and now you'd be getting $750 a month. You would no longer get welfare checks, and you'd pay 1% in taxes. In this case the marginal tax, when you combine de jure and de facto taxes, which is the amount that you otherwise would have that winds up with the government for taking on this basic level of work, would amount to $407.50 a month plus the full cost of working full time as opposed to not having to work at all. That is 54%, not counting the cost of lost free time.
In any other position in the labor market you might have a 10% marginal tax rate if you got a gigantic raise. A 54% tax (which is understated as per the lost time) is a HUGE disincentive to go back to work.
So make it a normal human marginal tax rate, and the only way to do this is to ease poor people out of welfare via negative income tax brackets.
The reality is humans are homogeneous enough that if there's something that lazy people can take advantage of, there will be lazy people and they will take advantage of it, and thusly providing opportunities for lazy people to take advantage of you is a systemic flaw.