We do have Catholic radio stations in various parts of the country and there is EWTN, of course. But, all such apostolates are founded and funded by private Catholic individuals and groups.
In order to have ads for Catholicism itself, the various dioceses might have to fund them, which means hiring professionals to create them and then the buying of air time at local TV stations.
If we want national ads, the United States Conference of Catholic Bishops would have to approve it, set up a committee to find funding, etc. Maybe if we put the idea before the USCCB, by convincing enough bishops that we need it, they will want to do ads. It’s possible no one has yet suggested it to them.
I believe they have done pro-life ads, but none that I know of that promotes the Church itself. I tried going to their website to find out about any TV ads and all I could find was something about ads for Spanish speaking people regarding family relationships. Hardly the sort of thing we are discussing here, though, is it?