There are two different issues at play here.
The first is unscrupulous employees. They may have various reasons for not joining a company as planned, but I suspect in many cases it is purely money. They are only motivated by how much money they can earn, not in doing a job. It is unlikely you would want to employ one of those people anyway, as they would not be productive in your organisation, and always seeking the next step up the ladder.
The second more serious issue is unscrupulous employers. A search of this forum will yield a huge amount of hits from people who joined a company and wanted to leave shortly after due to the job being nothing like what it was described as at the interview, management treated them badly, training opportunities non-existent, pay not as promised, leave policies onerous, and no clear path for advancement. It is a perennial problem which brings posts several times a week from people seeking help.
So I would say to you, STOP blaming the candidates and start looking within your own organisation.
Look at what you are telling candidates. Are you being honest with them? How does your organisation compare to others in the same field? Are you paying enough? What is the career structure? What sets your organisation apart from the others and WHY would anyone want to work for you?
As I have said over and over and over again here on CiteHR, YOU WILL NEVER SOLVE THIS PROBLEM without a comprehensive and robust recruitment and selection process with all staff trained to use it. I can guarantee 100% that most of the problems you have getting good staff is down to this one thing. How do I know this? I've been a member of CiteHR, and most of what I read about recruitment of staff here just appals me. And yet, week after week so many of you are posting complaints about poor staff. Go figure.
I have no doubt this happens all over the world, but I see no strong evidence in other parts of the world. It seems to be more prevalent in India. When I was working, there were three organisations I had involvement or experience in the recruitment process. We had almost no attrition, and staff that I was involved in recruiting stayed for many, many years. We weren't perfect by any means, but we chose new staff carefully and treated the staff well.
Finally, taking people's original certificates and holding them till they join amounts to blackmail in my book, and just breeds resentment. Candidates would be well advised to steer clear of such an employer, as it is a good indicator as to how they might treat you later.