Of course this statement is not really 100 percent accurate, but I've encountered agents who would book NWA into a KKK Christmas party for a buck.
You see, most agents and managers work off a percentage of the artist's income. Therefore, most of them inevitably try to increase their profits through "tricks" in the contract making.
It seems to me that entertainment is just about the only industry where you know going in that you're going to get screwed and the main objective is to minimize the screwage. This is one reason why it's not only important to have contracts but also the ability to decipher and interpret them.
Written contracts are always necessary in the entertainment industry! Whether it's a booking, management or recording deal, the first step is usually in verbal form followed by a written contract.
Though I have heard of isolated cases of folks within the industry who work with nothing but a "verbal understanding," I've never met any of them, but I never hang out at psychiatric facilities.
A contract serves to solidify an understanding between parties. As time passes, the two parties might have different ideas as to what constitutes their agreement.
By getting it in writing, there are fewer disputes over the agreements of the contract. Later, if a dispute arises, written contracts are much more enforceable by a court.
Lawyers are needed when you are not sure or unclear about the language of the contract.
If it's a simple booking contract or just a general agreement, a contract doesn't have to be that elaborate or drawn up by a lawyer. What needs to be clear, however, is all the terms that the parties have agreed upon.