License plates are supposed to make it hard for thieves to run away with a stole car too. And yet in Brazil it is common for cars to have fake license plates. The police is unable (or unwilling) to detect these. So:

* How would they detect a car that *does not show on the radar* because it does not have the tracking chip;
* And if a car is stolen, disabling the tracking chip is bound to be easier than filing out the serial number, which is common practice.

I'm sure tracking taxpayers will create a new source of tax revenue for the government, beyond the already huge load of tax on cars (60% of the selling price in Brazil). I'm unconviced, though, that the government is concerned with thieves or tax evaders. These are not sources of tax revenue.

That seems to be the painless alternative to check their status on any phone regardless of brand. If you're thinking Apple, there are apps that that enable generating update emails/SMS from the client (phone). This would save you the need to configure each of your machines to send the updates. You would only need to set up SSH. Check http://www.hiteksoftware.com/sshmobile/ssh.htm for an example.