at the end of the day its your property and you have every right at least to watch and learn what is going on.
...As long as your right to learn is being exercised in your hangar, with your facilities, and the person from whom you are learning is being fairly paid for the teaching time too!
Perhaps it can be presumed that everyone has the right to obtain a proper maintenance environment for their aircraft - exercise that right, and make the arrangements. Otherwise, it seems logical to select a maintenance service provider who has already put all of that in place.
As an aircraft owner and customer, you absolutely have the right to dictate the terms of the business you do, have work quoted, and have a detailed and accurate report of what was done, and how it was charged. And you have the right to expect that work to be of quality, and fairly priced.
As a maintainer, that person has a right to expect to be fairly paid for the time they apply to your aircraft (aside from correcting a defect they could have accidentally created). The maintainer also has the right to expect that all of their expenses are covered within the scope of the work accomplished. For my experience (with about twenty different maintenance shops), I don't see anyone getting rich maintaining planes. I do see well run shops, who charge fairly (meaning they profit) surviving to be there for the next owner who needs work on their plane. Interestingly, when I see shops who seem to flourish better than others, it appears to me that the maintenance service I am considering is linked to either aircraft sales, and/or a bustling flying service.
On the whole, 7k sounds hi for annual maintenance for a 172. But not knowing what was done, and what the aircraft needed, it becomes a "how long is a piece of string?" question. There are many necessary things which could take the bill that high, particularly if they have been deferred from past years. It's to some degree a matter of the starting point.
A friend who has a completely rebuilt and modified C 182 amphibian, spent hundreds of thousands of dollars restoring it, and modifying it to be exactly what he wanted - it took several years. The total cost well exceeded the price of a new 182. (Even he did not plan that!). But he smiled, and paid the bill. I remarked to him that the work accomplished, though very expensive, was an investment in piece of mind and snag free reliability. That plane has never had an in service failure, and has now gone through three annual inspections, with only one snag once - a broken engine primer line. Nest for him, it has never left him stranded in some of the very remote places he flies. I have never heard him complain about the cost of maintenance.
I consider all sides of aircraft operation and maintenance before I assert that something was "expensive", as some things are too cheap, and thus even more worrisome!