Child car seats in Mexico?

I know a family that is taking a trip to Mexico. Cozumel, I believe.
Is there anyone here that is either from Mexico or has taken a trip there
with a little one? I can't remember how old her little ones are, but I know
they're both fairly young - still in the forward facing/20-40lb car seats.
She's heard all kinds of "horror" stories about the taxis and all that and
how most don't even have seat belts... and taxi drivers tend to get real
angry if you do bring a car seat and strap it in to the taxi that does have
belts.
Does anyone know anything about this from first hand experience?