Totally agree, it’s not an ideal situation for the contractor or the government. The question is more whether the government (or your employer as a proxy) should play a protectionist role and handle the withholding for you, or if that should be your responsibility as a contractor.
Speaking from personal experience, it’s much easier said than done. When your rent is due this month, taxes are due next year, and you’ve only got enough for rent... you aren’t gonna withhold 30%. It’s not because you don’t want to, but because you just don’t have the money. Call it poor financial management or whatever you want, but the reality is that lots of people get into this situation. Yet I doubt many of them would blame their clients (or Uber) for the problems. Most would say the government demands too much tax, or they can’t find enough work.
Personally I would be in favor of a $30k annual basic income and eliminating all taxes on up to $100k in earnings. It will never happen, but it would be one of the best things to happen to society in a long time.