At least you technically never have less money from more work (but only if you consider bureaucracy free; there is severe bureaucracy especially for those that fluctuate in and out of coverage).
When the effective marginal tax rate is high, this is often as close as makes no difference, because you not only have the cost of bureaucracy but also the cost of working. You're paying an effective marginal tax rate of 80% so nominally you get to keep 20% of your income and have the incentive to work, but working requires you to commute, so you have to buy transit tickets or maintain a vehicle.
And because you're now spending your day working, you can't use that time to prepare food or maintain your household, so you may have to pay someone else to do some of those things -- but their entire compensation has to come out of the 20% of your pay you actually get to spend, so this can easily eat the entire thing and make you better off to not take the job.
been there, done that. it's not severe, it's not even 2 hours per month and maybe waiting for 2 or three letters from xyz.
2 hours of non-engaging bureaucratic work for 1300 € per month. Thats 650 €/h ...
It's not that bad if it's steady; but if it's fluctuating you easily spend a couple hours each month. And for at least some people, that type of work is far worse than their occupation of choice.
To give a sense how much benefits code and tax code have in common, see this worksheet for SNAP eligibility, which resembles a second tax return: https://www.fns.usda.gov/snap/recipient/eligibility. You get to do something similar, again(!), for Medicaid.
The American benefits code is a patchwork of conflicting sensibilities of the electorate: the smallest possible tax, paternalism and suspicion against the poor, plus a few policy analysis trying to obtain the maximum poverty reduction within those constraints. The result is a thicket of means tested programs with extremely steep phase-outs and a lot of paperwork. The all-in EMTR for an American with income between 0-40K a year is chaotic beyond reason as a result as they roll up the income spectrum.
This person who gave the presentation is indeed in one of the worst cases for the code: a single parent with multiple children.