I just found this thread. What interesting reading.
Somebody asked the critical question: What is the point of having a contract if it can be cancelled at any time?
Also, somebody said "... so I get paid ...."
The cancellation question negates any value in your contract. I think the OP even said it bind the customer to nothing. If this be the case, why bother? Contracts are established to bind two parties to something. When the document does not bind anything, then it is worthless. A simple letter of understanding of the services, with prices, is adequate.
What good is this document when you show up at the property, and another contractor has just been there to mow, remove snow, trim bushes, or some other service? Who is going to bother going to court over the small dollar amounts of these services? I don't think the OP is considering a $10,000 landscape install, rather simple, menial tasks of mowing, trimming, or snow removal.
As far as being paid, the honesty and integrity of the homeowner will determine whether you get paid or not. Having such a document does nothing to assure getting paid. Yes, the pricing structure is spelled out, but the simple letter of understanding does the same thing. Even if you file a small claims court case, the only thing you will gain is affirmation that your bill is unpaid. Both parties know this before going to court. The court does nothing to get the outstanding money into your bank account. Neither does the document proposed by the OP.
Trying to establish a legal relationship with your customer base creates a less-than-personal business relationship. Presenting such a document for lawn mowing fosters a tone of lack of trust. This happens right at the onset of the relationship, "... I may not trust you, so we need to have a legal, binding document to cement the relationship...." However, since it is not even binding, the tone has been set for no good reason.
In my 18 years of service, I have never been asked for a contract.
If somebody came to my door wanting to mow my lawn, and gave me such a document, the only outstanding question would be how far away would the laughter be heard.