Assuming that the non-custodial parent was properly served, and made aware of the court date, they are expected, and demanded, to show up to court. Typically, a summons, along with other relevant documents to that court date, will be included in the service, and will also notify the parent of the date, time and location of the court date.
There are certain types of cases in which the penalty for not appearing can lead to a bench warrant being issued for that person’s arrest. However, with regard to custodial/non-custodial parent issues, if the non-custodial parent does not appear, it will only serve to hurt them in the divorce process. Suppose that you are the non-custodial parent, and the court date is set to discuss a potential modification to the custody agreement. While it is not a guarantee that, if the non-custodial parent does not show up, the court will rule in favor of the other party, it is really not a good look for the non-custodial parent, and is not indicative of someone who A. is responsible, and B. really wants to have a new custody arrangement that will allow them to see their kids more.
If the court date is to discuss child support, then the non-custodial parent’s absence could mean that the court makes a decision without the non-custodial parent being able to represent themselves and their interests in court, which could be incredibly important, depending on the exact nature of the issue being discussed in court. So, besides giving off the impression that you just don’t care, missing court dates means that you will not get to have your interests represented and argued for, which leaves you at the mercy of the decision made by the court – without you.