It is a combination of a shortage of priests and huge dose of modernism. Most adults under sixty have been catechized under a culture that has been largely shorn from its Catholic roots, and most people either don’t know (“Wow! I hadn’t heard that before!”) or don’t care (“They don’t really mean that!”) what the Church teaches on this or many other matters.
On the priestly front, not only the shortage plays into it, but the bureaucracy. So many pastors have been turned into administrators and accountants, attending numerous meetings at the diocesan and parish levels. Their days are taken up with a good deal of CYA, red tape and other factory functions that they do not have much time for the primary reason of the priesthood: Mass and the sacraments, along with truly pastoral work (visiting families, tending the sick, etc.). This is not the fault of the priests; it is a secular trend that permeated the Church and began to dictate the expectations of bishops and others. However, I am convinced that for a priest today to be truly holy, truly pastoral and truly sacramental, he needs to buck the trend a bit and take command of his daily schedule. The priests today that I know who do this are the ones who make themselves available in the confessional, for annointing of the sick, funeral home visits, etc. These are their priorities, and while they occasionally fudge on the administrative aspects, they do not completely neglect them, but they see the salvation of souls at the top priority. They usually are not the types who become bishops (or even monsignori), but occasionally they do. Either way they see their roles in common with the saints of centuries past, not in contrast
As for the modernism, people have been so poorly catechized that many honestly believe that they do not need to confess very often, if at all. In an attempt to “update” teaching methodologies, the sense of sin was de-emphasized and personal guilt overlooked in favor of social and corporate sin. Nations and corporations and even the Church are guilty of XYZ, but individuals never seem to be. For some people this is simply a matter of aloofness, i.e., no one has ever taught them otherwise. Westerners in general, and Americans in particular, have lived in relatively prosperous societies that have much to say about the pursuit of wealth and pleasure, but little about personal obligations. Consumerism fills the void created by the absence of a moral compass. Unfortunately, many seminaries, and therefore many priests, bought into this and the result has been the eroding of a sense of personal sin and the obligation to confess.
Yes, if you build it, they will come. My parish priests hear confessions every day, seven days a week, before every Mass, and with slots scheduled during a weekly holy hour, plus Saturday morning. The result is that there is always someone confessing, even though it is a small parish. They have been trained and nurtured this way. Sure, there are a few scrupulous types who need periodic prompting, and the pastor does this with confession cathechesis printed in the bulletin, and occasionally from the pulpit. And I don’t mean just EF priests. The holy priests that have motivated me, EF or OF, have believed in preaching about the importance of confession, and then making themselves available in the confessional, regardless of what meetings and events were occurring in the parish and diocese. It may be a matter of reclaiming our priests as sacramental celebrants, teachers and pastors, above all else.