Your summary of the reception of The Shawshank Redemption doesn't seem to fit the wikipied article you linked to

> Leading up to its release, the film was test screened with the public. These were described as "through the roof", and Glotzer said they were some of the best she had seen

> nominated for several Oscars in early 1995

> It went on to become the top rented film of that year

"Best movie" lists tend to have films with both critical acclaim and audience appeal.

It got critical praise but was a flop at the theater. The home video market redeemed it (haha) with audiences. From the article:

"Despite its disappointing box-office returns, in what was then considered a risky move, Warner Home Video shipped 320,000 rental video copies throughout the United States in 1995. It went on to become the top rented film of that year. Positive recommendations, repeat customer viewings, and being well received by both male and female audiences were considered key to the film's rental success."

All 3 movies (It's a Wonderful Life, Groundhog Day, and The Shawshank Redemption) had critical praise upon their initial release. Groundhog Day was even a solid hit. But no one could've predicted what they became later.