Mexico - immigration oddity

[CharlieCrocodile]

I've just come back from a week long holiday on Cancun. Upon arriving at immigration they didn't want to see my landing card and simply stamped my passport and waved me through giving me back the landing card without any marks/notes/stamps

Expecting to hand over the immigration card upon leaving no-one was checking them at security. Neither do I have an exit stamp on my passport.

Is this the normal immigration process in Cancun?