I don’t want to be unfair to sspx priests. I can only say that from a pretty active participation with the Society from 2005 to 2012 in Post Falls, we were not aware of priests going door to door. Much less did we ever find priests, of the always 6 or 7 priests stationed at ICC, doing acts of charity like going to hospitals, rest homes , jails, mental health facilities, and doing other acts of mercy outside the parish - with the exception of one. And what he did, for the most part, was to bring Communion to shut-ins from the parish, as well as to visit ICC parishioners in hospitals parishioners occasionally.
If there are sspx priests currently participating in charitable community service ministries, then it must be elsewhere.
First of all, your 7 years experience only covers Post Falls. There is a wide world outside that locality.
Second, SSPX priests are too few in number to collectively excel at all 14 Works of Mercy (7 spiritual and 7 corporal)
The Conciliar Church has "the body" well taken care of. The SSPX specialized in those neglected Spiritual works of mercy -- especially instructing the ignorant, admonishing the sinner, counseling the doubtful, praying for the living and the dead. Think about it: the Novus Ordo completely doesn't pray for the dead; they have them in heaven already!
As for visiting hospitals, prisons, and what not, we should be careful to criticize ALL priests with a broad brush. You'd have to point to something the priest shouldn't be doing, where he'd have more time to minister to various groups. SSPX priests often have to teach and/or help administer in SSPX schools during the week. That is time well spent. The SSPX can only spend his 15 hours a day once, just like any of us. The SSPX priests already have daily Masses to say, correspondence with Faithful, their daily breviary, Spiritual Duties (spiritual reading, Rosary, meditation, Scripture reading, preparing sermons, personal prayers) plus normal personal care (eating, showering, bathroom breaks, etc.) Most SSPX priests have a certain amount of travel each week as well.
And I question the value of going in to some random prison that no one asked you to come to. Many SSPX parishioners get insufficient time with their priests already. In the Trad world, there is a real priest shortage for things like advice and spiritual direction. The priest can only be in one location at a time, during which time he is literally ignoring every other location on earth. He has to prioritize and make choices.
If a priest is wasting his hours away (socializing, recreation, sports, TV, etc.), then he is to be blamed. But I will only criticize such priests individually. I'm not going to complain in a general manner, because that's silly.
Maybe it's the same reason we haven't taken back the world, or taken back the Church yet:
Because we can't. i.e., we have insufficient manpower and resources.