Roughly translated. Its our (the author of the sign) car park not Mc d's. We just allow them to use it. If we (the author of the sign) want to park a car across the entrance to stop you getting in or out tough s**t.
Thats how I read it.
We are sick to the back teeth of people parking in our carpark for nothing and going across the road to Mcdonalds or going places. Just because its quicker , it doesnt give you the right to walk across this carpark to get to mcdonalds. !!
The reason for this sign is to prevent what is called "existing usage" from being established and that the cost of protection. like wheel clamping and towing is not stated but implied in the sign.
It is written in "court speak".
Dont park here if you are a patron of _______ and dont assume you have the right to park here just because there is a space.