"Why would you say they are stretching the limits of the law? My understanding is that they had no obligation to renew those 3-month contracts."

Because these 3-month contracts were renewed for years, and in fact, there are many employees who were employed for over 3 years, continuously, by the company. That makes the non-renewal -> layoff.

    "Even if that's the case (highly probable), it would still be a huge improvement compared to the pre-efood era when lots of delivery riders would not be paid on time, work (illegally) with no insurance/pension, sometimes even get humiliated by terrible bosses."

Food delivery platforms are not in the business of providing cash and benefits to drivers. They are in the business of making money. But apparently, they cannot do either.