Now that you mention it, all of those Kryptonians are adults, right?
Maybe Kryptonians, as their bodies mature, are better able to process yellow solar energies? Like, as kids, they can barely do it, their "stomach" isn't big enough, and even if it were they can't handle that much of it. So minor trickle of power. But as they grow older, as their bodies mature, their "stomach" gets bigger and they can process more and more and more of it.
. . . Yes. I like it. Also would help if Clark ever got Lois pregnant. Why didn't super-fetus kick through Lois's body before it was born? Or why didn't super-baby's tantrums level city blocks? They couldn't, super-baby's super powers are miniscule. The older a Kryptonian is, the faster they get charged by sunlight.