I don't play the Macdonald's Monopoly, but I would like to point out a few things.
1) All the pieces of each colour except one is common. Yep, you heard me, park place is EASY to find. Thus, the 50/50 thing is not fair for the person who has the rare piece. To be honest, the person with the rare piece should pick up somewhere in the neighbourhood of 70% if it's a 2 piece, and 60% in the case of a 3 piece.
2) All the rare pieces are ABSURDLY hard to find. Which is why I mentioned the above
3) If you live in Toronto, your odds of winning are even lower than normal. Because the Macdonald's where my buddy works needed cups when they didn't have any, so they used Monopoly sticker cups but took off the pieces. Turned out, they filled out the entire board