I’ll tell you something about Jim who doesn’t want to come to the company parties. He thinks if he does a fair day’s work for a fair day’s pay, that is all he owes you. He doesn’t think having a job means the company owns him, body and soul. Even if he knows that not attending the parties means a black mark against him, he still won’t go.
I’ll tell you something else. Before I retired, I worked for a lot of different organisations, some large, some small, and there were always some Jims. They got along well with their co-workers. They did their jobs and did them to the best of their ability. They were often prepared to go above and beyond the call of duty at work. But that was where it stopped.
Here’s the thing though. In every organisation, for every Jim, there are at least 25% of your staff who are Jim wannabes. They all wish they had the nerve to say no, but they don’t want to risk their jobs or their pay raises or their promotions, or even just the disapproval of their co-workers. They won’t tell you this because, as we can see by your question, in your mind this is not somebody exercising their right to say no to a social event. It is a problem that needs to be “handled”.
They don’t go home from the company party and say, “Wow, what a blast.” They walk in the door limp with exhaustion and say, “Thank god that’s over!” They probably put on a convincing act while they were there, but they didn’t want to spend their private time with a bunch of people they are already spending at least eight hours a day with. If they want to party, they want to do it with family and personal friends.
If you want to “team build” either with parties or other activities, do it within regular working hours. Jim probably still won’t like it very much, but at least he is getting paid for it. And it will not be breaking into the precious free time he needs to recharge his batteries so he can be an effective employee for you.