Quintana Roo state currently seems to require about $45,000 USD:

A single fatality can incur $22,723 criminal court, $22,723 civil court = $45,446 total

At MXN 13 to USD $1.00, that's under half a million pesos.

That being said, Mexican courts have increased the maximums for death to 5,000 days calculated at the minimum wage.

And rental car company policies can require anything they want.

Ask to see the documented requirement, and yes, be aware many companies will lowball and not disclose much on their sites. Who's going to hold them accountable? Probably nobody.