That's the way it normally works.
The union gets to represent workers for a couple of reasons. The biggest is that companies don't want to negotiate a separate deal with union members, and a different deal with non-union members - or worse still a different deal for each employee. It makes for too much complexity, it raises all sorts of legal complications, and it raises resentment if the union deal ends up being better than the non-union deal. You should also remember that this is a negotiation about the whole pay structure, not about each person's individual compensation.
Even if there was no union, companies don't negotiate separate deals with each employee. You might get a merit increase, or a one time bonus, just for you, but you won't get extra vacation days or health benefits just for you. (Unless you are in a very small company, which are almost never unionized.) There is nothing stopping you negotiating separately for a merit increase or one-time bonus, if the company pay structure permits.
The good news is that a union is almost certainly going to get you a better deal than you are going to get on your own. Unions have lawyers, professional negotiators, and the power of numbers behind them. So the best way to think if it is that you are getting a professional organization to negotiate for you, for free, and you reap the benefits. There's a chance they will negotiate something you didn't want, like benefits you don't need, but there's a chance that will happen anyway. (That's another good reason why you don't want there to be two separate deals, one for union members and one for non-union. The non-union, meaning you, will usually come off worst.)
If you want to have a say in how the union negotiates, you can always join them.
There is nothing stopping you attempting to negotiate your own private deal. The likelihood of that succeeding is about the same, with or without a union.