I have fallen victim to a scheme of inflated postdoctoral salary, detailed in the thread below:
Persistent issues with salary pay as a postdoc in China: What can I do?
Regarding the core of your question, this is a direct example of how a higher salary should not be a relevant strategy to attract postdocs. I should state I was not attracted as a postdoc primarily because of the salary. My country was sliding down a serious economic & political crisis, and as an adventurer I was greatly interested in trying my luck in China. Moreover, I believed one of the PIs involved in the project was a good scientist. I kept pushing for a higher salary merely as part of any job negotiation, aiming for the best offer.
What this institution and relevant PIs do is declare funds which are strictly reserved for project expenses as promised salary, in the hopes of attracting the best possible postdocs. I believe this is both bad and stupid practice strategy, for the reasons below:
(i) I believe the best scientists seek the most interesting & exciting scientific environments because they are moved by passion; (ii) any conflict over salary pay and research expenses will destroy necessary focus on complicated technical discussions and procedures; (iii) attempting to buy scientists will corrupt their interests, resulting in biased scientific output.
Had these professors honestly declared the actual smaller salary and the available project funds, I'd have accepted the offered conditions and joined them as a postdoc anyway. In the absence of conflicts over salary pay and project expenses, I'd have focused entirely on the project ideas I had proposed, resulting in fair collaboration and interesting output.
In the end after leaving I now try my best to prevent other colleagues from falling prey to similar schemes. I am counter-advising any scientist to visit China, as I believe a local money-centred culture is corrupting the field.
A trivial example is the local practice of paying prizes$$ per published paper, which I have seen resulting in colleagues openly negotiating authorships as commodities, not only among each other but also with journal editors and local staff.
I firmly believe universities cannot work for-profit, and that high intellects cannot be bought.