Remember when we all used to stuff towels under the drafty door in my old apartment? That was our "foam seal." Andreww30 is right about older frames shifting. Our whole building settled, so the front door had a huge gap at the top. The foam tape was the only thing that could squish into that weird angle.
You mentioned the vacation home's perfect seals, but that's usually because the frames are new and straight. Older door frames often have shifts or gaps, so you need a seal that can stretch to fill them. I'd start with a simple adhesive foam strip to see how it fits your gaps.