I found a REALLY GOOD post on another message board about this same topic. She is responding to the first paragraph, in italics.
Like it or not, we live in this society. It's impractical, irrational and impossible to behave as though we were living in the same society our grandparents and great-grandparents lived in. We can't live their lives, much as we'd like to. That means that to some extent we do have to conform our current situation. Otherwise we're just living in some isolated little bubble instead of living our lives. And if a girl has to work to help pay her way through college (or for whatever reason) and it's a choice between wearing non-immodest pants and losing her job, the practical thing is for her to wear those pants since there is no sin involved.
Well, if the person doesn't know it's a sin, then usually it is not a sin (hey, but if the person doesn't know it's a sin to dress for the purpose to provoke lust, but they know it's a sin to have lust in one's heart, by their intent they are sinning --- even with their hardened conscience, yes it's true). But for something like wearing pants because it's what the boss wants, then it's an issue of one's spiritual, interior disposition. If one is less zealous, then the sin could very well be that of spiritual sloth. Now, that's not condoning disobedience to one's superior, but there are other jobs out there.
I know a woman who did NOT live with her parents and supported herself. When she was laid off (along with over 7 thousand other employees from the same company --- mostly in her local area), the only good job offer she received was in ... guess what... the FASHION INDUSTRY out in a city that had a very liberal culture. The job would have had her working long hours, and often "on call". There was no regular 24/7 place to adore our Lord in the Blessed Sacrament because it was a big city, so she made one of the most difficult decisions of her life: to not accept the job. This decision she made having no job lined up, and NO FAMILY to help her. She knew that it was not likely that she would find a job in her industry in that area, and that she would be working entry level temp jobs for about half what she used to make. This woman sacrificed more than you care to know, but many other people make such sacrifices, too, for the love of their Lord. She still works temp jobs that are even entry level (making less than half what she used to make and struggling to survive), but she has lived according to discernment of God's Will, and for a higher good than anything the temporal world can offer.
Choosing to wear only skirts is a small sacrifice. Many good Catholic families often make greater sacrifices frequently, simply by living a good, holy life. They choose to do the holy Will of our Lord, against what the world would have them do. They are open to new life, and prefer poverty than to hold off having more children so they can go on more trips (or any), or have a new vehicle. Many of these holy mothers homeschool their own children, which is a tremendous sacrifice, since the mother never has time for herself. Her joy is in Christ, in through Christ for her children's welfare. This she considers greater than her desires for herself, to the point that her very desires for Christ and for her children is her life. This is a daily, committed sacrifice. If we cannot make the small sacrifices, how can we be successful at the bigger ones like those of these holy women?
I'd imagine that there would likely be another supermarket that would allow her to work wearing a long skirt.
While it is true that we don't live in the same society that our grandparents lived in, that doesn't make it right for us to assimilate to the spirit of today's culture. Its collective conscience is hardened, and there is little to no room for true submission to the Kingship of Christ.
What is impractical about wearing a skirt in a job where you are simply standing most of the time? Does a skirt make it harder to stand? What seems impractical is that it doesn't allow one to assimilate into the culture in the sense of being accepted in the "norm", but we don't need to be accepted by the general populace who lives by the spirit of the world, rather or at least more so than by the Spirit of Christ. We are called to be signs of contradiction, not signs to show we are just like everyone else. We are living for something that is a higher good than what the world can give us, not that public acceptance doesn't have an attraction to many who are so disposed, but to be seeking it is not to seek the will of God. We are not supposed to be concerned with human respect, but with what God thinks. God has made man and woman different in such a way that we are physical signs of a spiritual reality. Wearing clothes that either diffuse this truth, or exploit this truth in a perverse way are not living in accordance with Truth (he that is Truth).