That is a very presumptuous observation. Reviews are subjective by definition. I have also spent a certain sum of money buying apps I could not return, despite the great reviews. For instance, many apps have very backwards UI's that I have no patience for, but some reviewers are seemingly OK with.

Apple certainly doesn't owe anyone a trial system, but more than anything I find it odd they don't see the value of it. For instance, it would arguably result in far more impulsive purchases.