I've used the site many times for small jobs (logo designs,...

I've used the site many times for small jobs (logo designs, graphics, website building etc) and have never had any issues.

You choose the Freelancer you want, literally out of 100s of bids. I always chose a fairly priced Freelancer who had plenty of reviews and a solid profile (achievements, accuracy, speed, language proficiency etc).

The Freelancer profiles are like eBay profiles: the users spend considerable time building up their ratings, reviews and portfolio and they aren't going to ruin that by taking some milestone payments and leaving.

As an 'employer', I can't just 'disappear'. My credit card is linked to my account and I will still be charged.