Whilst I fully accept that Joe Public may not be entirely happy about someone who has offered to pay to be in the pointy end, there are two things that I think worthy of note here:
1/ A pilot who has paid for a type rating necessarily HAS the qualification to show that they are safe to fly commercially. The comparison with a trainee dentist, therefore falls apart, because one HAS the professional qualification, the other is working towards it. Further, as has been pointed out - and ignored - endlessly, there is no such thing as a truly "paid for" rating any more. Either you stump up the readies out of your own pocket up front (a la Ryanair) and get a reasonable wage, or the employer pays the TR, but you get a reduced wage for x many years, a la BA. In neither case is the TR "free" - you're paying for it, it's just how.
2/ There is a deeply unpleasant implication in these posts that anyone who has paid for a TR themselves is -defacto- an unsafe pilot, whereas anyone whose company has paid their initial TR is a safe pilot. The flaws in this logic are huge and obvious. If you can't see the elephant in the room of this argument, there is little hope for any of us. A 200 hour graduate is a 200 hour graduate and liable to make the same mistakes regardless of whether they can pay for a rating or not.
Granted, there is an argument that says perhaps those with the cash to pay a rating are able to steal a march on those who are more able, but less cash rich, but then it's equally true to say that the most competent of pilots may be able to afford a TR and the monkey who took 15 attempts to pass CPL can't afford it (especially if they had to pay for those extra 15 attempts!). All of this of course, is based on paying your TR to land a job. The world of line training schemes is a different beast altogether - and a loathsome one at that. But, then - who is to blame for the rise of these?