Deep dental injections: Why do I have to be numbed up after an implant healing cap is removed for an abutment placement?

Implant abutment. In most cases once a healing cap has been in place for about 2-3 weeks, the tissue is healed enough to have the abutment placed without local anesthesia. If placed sooner, the tissue is still somewhat raw and therefore sensitive. Also, if the implant is placed deep subgingivally, there is compression of the tissue during seating causing pain. The biggest factor is individual pain threshold.
Normally you don’t . Most people do not require anesthesia. Some people are more sensitive and require to be numb .
Incision. There is an incision that will be made to gain access to the implant. The anesthetic will not only prevent the pain of the incision, but it will also control the bleeding so that the surgeon can see what they are doing. Usually the injection is superficial in the gingiva surrounding the implant. It's a piece of cake.
Good question. You don't need a nerve block to uncover a healing cap. If it is totally healed over, a little local next to the site should do it. If the healing cap can be seen, then it is even easier. Sometimes topical ointment will keep you comfortable. I doubt a deep tissue nerve block is in your future. Perhaps you misunderstood.??