Yeah. When I've been called to replace a kicked-in door, I just remove the whole door, jamb and all, and inspect the framing carefully. Sometimes I'll end up replacing the jack stud as well. Usually the strike jamb is beyond rescue, and I end up replacing the entire door, but the economy-grade steel doors have been coming with jambs made of soft pine or spruce, hardly strong enough for normal use, much less to resist being kicked in. I can sometimes improve that by screwing a wide Simpson tie strap to the back of the strike jamb above and below the strike itself.
If it was my job to install a door so it couldn't be kicked in (using off-the shelf materials), here's how I think I'd do it. Starting with the framing, I'd lag bolt and construction adhesive the solid header, king studs and jacks together as a unit with an extra king on the strike side, then lag bolt it into the top and bottom plates (or Timberlok screws). I'd frame it up straight, square, and tight, to minimize shimming. Then I'd choose a heavy lumber core solid door in a doug-fir jamb, and lag through the thick (outer) part of the jamb every foot or so vertically, counterboring the lag holes to sit flush with the jamb face. I would cover the bolt heads with an additional stop, 1/4" thick with a 1/4" reveal on the outboard edge, glued and nailed to the jamb face.
I always replace the top hinge jamb screws with 3-inchers, but for added security I'd do that to all of them, and the hinge door screws as well. I'd also insert 3 4" lags into the hinge jamb until they protruded about an inch, cut the heads off, and round over the stubs. Then I'd bore three holes in the hinge edge of the door to accept them.
Finally, I'd install two keyed-alike deadbolts, one each above and below the lockset. Then I'd case and detail the opening as usual. I know, I know, some members will say "chainsaw", so I'm also installing a 30x74x1/4" steel plate on the inside door face, screwed every foot around the perimeter.
I'd also consider installing a crossbar, brackets bolted into the king studs and padded so it contacted the inside door face and supported it to within about 2" of the edge. It'd be kinda ugly though, and only usable from the inside, and might be an obstacle to exit in case of fire.
Anyway, I think I'd be willing to tell the owner, "If you can kick this door in, I'll fix it for free." I'm not saying that it couldn't eventually be breached by a determined intruder, but he better bring a lunch. And it would look pretty ordinary from the outside, except for the double deadbolts.
Parker