Funny how foreigners can't read "Tip"

So I currently work out at a pool in Las Vegas.  Mind you it's the desert and it's August, so it's HOT.  Serving drinks poolside is a whole different ball game.  It's busy, people are drunk, cranky, and did I mention it's hot!  It never ceases to amaze me when I present the check for a guest to sign to their room, that the only line guests can NOT read is "tip".  There are 5 lines on the check:
Tip:

Total:

Print Name:

Signature
Suite #

Don't you think that it's funny that guests who can't speak English can complete the lines that say "Print, Sign, Room #" but can't seem to understand the tip and total?  When I hand it to them I say "please total that out for me and sign" and they just sign and print.  Then I point to the the tip and total line (which I have placed "x's" next to) and say "I need you to write in the total" and they proceed to write in the exact total and don't even touch the tip line!  I've gotten to a point where sometimes it's just so hot that I don't even bother.  I've just come to expect that if they are ordering orange juice and coke with no ice then they aren't going to tip me and I move on to their english speaking neighbor who's ordering shots of Patron ;-)