I think a contract without a probationary clause is okay, and I think a contract that has a probationary clause is okay also.

Naturally, I agree with what you've written regarding the need for Chinese employers to be more reputable. As per JN's most recent post, however, I believe a more thorough screening process in terms of hiring is also needed. But yes, less corruption, more accountability and, most definitely, a larger focus on the needs of the students and less focus on the bank account would be a good starting point.