Besides the fact that IT is one of the most safe careers for Catholics, it's relatively accessible (without incurring 100K+ of student loan debt), it's usually a family-friendly career (not a lot of out-of-state travel like sales, or days/weeks/months away from home like truck driving or the military). It's also extremely safe. How many wives of IT men get a horrible phone call or knock on the door informing them their husband was maimed or killed on the job? Anything involving car travel is *extremely* risky, much more so than air travel. And military, police and firefighters die all the time. Construction involves a lot of powerful, dangerous equipment. Even factory/manufacturing jobs involve a lot of very heavy, very dangerous machinery.
What do IT guys get? Carpal tunnel or maybe obesity. But that's really nitpicking, because those are things one would suffer from even if they didn't work (say, if they won the lottery and retired at 25). In other words, the risks and "first world problems" of rich people.
But it should also be pointed out (and Ladislaus touched on this point) that IT is also a very high-paying career. Enough to accommodate the Trad men who want a career that can earn two incomes at once.
You know how most American households earn about $70K to $80K a year to make a living? And that is with TWO jobs, the husband and the wife? Guess what? Trads don't get some kind of "get out of jail free" card just because they want their wife to stay home, or because they want to have an above-average number of children (which, today, means "more than 2").
In general, Trads have almost the exact same suite of challenges, temptations, and problems experienced by any worldling chosen at random off the street. What does going to a Tridentine Mass for 1 hour every Sunday really do to exempt one from the problems of the present age?
It's absolutely true that virtually all families need that $70-$80K to get by (with a few exceptions). So how do you earn good enough money to do that with only one job? There aren't many options. Plumbing isn't going to get you there, unless you go into business for yourself. Ditto for many other "trades".
Unless your parents leave you some land or really help you out ("here's a house, a car, some land, a nest egg...") it's going to be very hard to support a large family on $35K a year.
You need enough money for food, shelter, utilities, clothing, education (sure can't just send em off to public school!), health care, at least one vehicle (and it won't be a so-called "smart car" 2-seater) and gas for that car (large vehicles take more), insurance for house/car, property taxes, maintenance (house/car/property), etc.
Health care is a big one. It's one of the largest items in most budgets. You can't just pay cash or hope for the best. Just one trip to the hospital could RUIN a person's finances. As in, you have a good credit score and $50K in the bank, you wake up one day with a pain in your side, and next week your whole savings are gone and you're broke and behind on your bills. Health care is priced in super-money that most people don't have. It's like a bunch of neighborhood kids playing "economy" and trading pennies for sticks, pretty rocks, leaves, etc. and one of the kids deciding to save up to buy a car. It's not going to happen with pennies -- it's an order of magnitude higher. Cars are priced a world above kids' money.
Likewise, people earn dollars; they might have $100 saved this month, another $150 saved the next month. But procedures in the hospital are priced in TENS OF THOUSANDS of dollars. Good luck saving up that kind of money with mere frugality. Health insurance is mandatory.