Having lived in and around Houston for 30 years, I believe there is some confusion going on.
In some strip malls, the shop owner does not control any of the parking spaces in the strip mall, but the owner of the strip mall may require patronizing at least one of the shops in said mall to gain the privilege of parking there.
In other shop/mall owner agreements, the shop owner has a right to reserve a certain number of places in front of his establishment for parking for his customers. Often, these will be businesses that thrive of short-time parking such as dry-cleaners. A dry-cleaner whose customers must park four stores (or more) down isn’t going to get the business as one whose customers know they will find a parking place in front of the business. Since they are only going to stay a few minutes, the business only needs 3 or 4 places to satisfy his customers. In theory, such shops pay a premium to the strip-mall owners for this right.
So, some strip mall shops have the right to restrict parking in front of their shop, while others do not, it depends on their agreement with the strip mall owner. All strip mall owners have the right to restrict parking in their lot to patrons of the businesses there.
Now, in order for a no-parking sign to be enforceable, it must meet minimum requirements. The Great Antibob has done a good job of finding cites for those.
My point is that if your friend is trying to say that a dry-cleaners “parking for dry-cleaner customers only” is invalid because it is hand-written and posted on a broomstick in a bucket of rocks, he is likely wrong. If you can see the sign and read and understand what it says, you can’t make a very strong case that you didn’t know the parking was restricted, which is what you would have to convince a Judge if you were to try to contest towing charges/impound fees/or other fees.
If my assumption that this is the situation, that your friend is trying to say you can ignore the Dry-Cleaner’s (or nail salon, or other specialty shop) sign in front of his shop, I have to wonder why? Unless you are the owner of the lot, who are you to question the shop owner? If the shop owner did not have such an agreement with his landlord, don’t you think the landlord would take care of the situation to collect more money or other shop owners would complain? If you don’t want to play by their rules, park somewhere else.
excavating (for a mind)