To be fair, this was when they were just coming into London and offering crazy bonuses to steal market share from Deliveroo, but still, this isn't controversial - if someone pays you bad wages, don't work for them...
If you can't find work elsewhere, you'd rather work for pennies than for nothing.
You could say the same about any regulation, if you cannot manufacture something at a reasonable price without polluting more than allowed, you need to change your prices or adjust your business model.
This is quite obviously a false dichotomy. Its not necessary bad when a job doesn't exist (e.g. the job 'head of slave labour team' doesn't exist anymore), and the obvious best outcome appears to be a fair wage for a (therefore existing) job.
Uber doesn't seem to follow local laws. For example [and this is really one of the many examples], in The Netherlands you need a license to drive a taxi which made UberPop illegal. Uber didn't care, they launched it anyway. This appears to be the modus operandus of Uber: shoot first, ask questions later.
The way they try to get drivers for Uber as documented here (again, in The Netherlands, article in Dutch use Google Translate) [1], underpaying them after they're in, is also disheartening and only benefits Uber; neither the customers nor the drivers. So what Uber did there was invest in driving their competition away. Of course, people don't wanna pay for pennies, but that's why they have the Uber brand. They use this branding together with state of the art technology to get customers (workers and clients).
The more this information gets out, the less victims Uber is able to make.
[1] http://www.taxibelangen.nl/ervaringen-ex-uber-chauffeur/