I can think of several other factors why people did not react to Columbia the way they did to Challenger:

Challenger had already happened.

Columbia happened on a weekend.

We were just over a month away from invading Iraq.

9-11 was still pretty fresh and much bigger and far more
personal in the minds of most people.

Unlike the Challenger school teacher, there were no previously publicly
"known" people on the Columbia STS-107 mission, plus the mission itself was not exactly headline news.

Yes, Israel was pretty excited about having its first astronaut in space, but how many people in the USA realistically paid attention to that?
Many people seemed surprised to learn that we were sending a probe to Pluto on January 19.

Not trying to diminish the space tragedies, just wanting to give an honest assessment of why the public reacted as it did. I think it just comes down to an instant oversaturation of news these days, especially bad, traumatic news.