This job has politics. You must appease your fellow technicians if you want to ever ask for their help or borrow a tool. You must appease and befriend your service writer if you ever want to stop getting all the crap no body else wants to do. You also should appease your customers. Once a customer has found "their mechanic", it becomes a special bond. They begin to bring everything to you, request that only you do it, and they want and expect you do things for free because you are now buds. Sometimes this relationship works out great with well tipping or connected customers or if you have a salary or hourly only paid position.
Borrowing tools was already mentioned earlier. If you borrow too often, you can hurt your friendships. If you forget to bring tools back, you will quickly become the "thieving" enemy of the shop and be blamed for every tool that goes missing.
Lets not just talk about shop politics. Lets talk about family and friends. Suddenly all your family and friends are asking you for advice or for help. For friends: I don't mind helping you out sometimes. Free information is no problem. I may even do the work for you depending on how much I value our friendship. Especially if you offer valuable services in the future such as I fixed your car so you offer to help me roof my house. That's how friendship works; give and take. Once it dwindles down to the point at which you are only ever contacting me for help with your car or you never make time to help me, your out. That's just the way it works.
Family is different. I try to help family members regardless. Family should stick together, right? Don't take advantage of me and things are all good. Sometimes my family members even extend my services out to their friends. I don't appreciate that. If you like fixing stuff for free, then this may be the career choice for you.