Unlike mainstream American businesses, more than half of which fail

Yes, there is no direct comparison because of the use of subordinate clause with 'while.' It gives what the situation is on one side and the main clause gives what it is on the other side. There is no noun to noun comparison as one would expect with the use of 'like/unlike.'

Unlike mainstream American businesses, more than half of which fail, the failure rate for businesses in the Amish community hovers around 5 percent.

Option Elimination - This is another good question to understand the deceptions. . Shraddha also pointed out that from a concept standpoint, the question is not difficult but tries to play with our minds. . Bottom line - focus on the meaning, and that'll never fail us on GMAT. Now, back to our question.
It's a deception because you see four options with a comparison trigger: "unlike," the cherry on the cake is the noun "the failure rate" in the non-underlined part. So our mind is fixated on the comparison, but then the last option is a U-turn and ditches the comparison, and straightaway gets into another more straightforward concept of subordinating + independent clause construction. But our mind is still fixated on comparison, and while E may look good, we'll still keep looking for something parallel to "the failure rate" or the comparison marker. I recommend using a Data sufficiency mindset here if that helps us. Take each option as independent of the other (GMAT knows we do a vertical scan. While that may be a good strategy for more straightforward questions, a high-quality question such as this one punishes that mindset). When you reach option E, while you can't eliminate "the failure rate" in the non-underlined, at least ditch the baggage of the "unlike" comparison marker. If we can do that, then option E is straightforward.


Option Elimination -

(A) Unlike mainstream American businesses, more than half of which fail - "American businesses" are not comparable to "the failure rate."

(B) Unlike mainstream American businesses, in which the failure rate is more than half -"American businesses" are not comparable to "the failure rate."

(C) Unlike mainstream American businesses, where more than half of them fail - "American businesses" are not comparable to "the failure rate." "where" is a location marker.

(D) While the rate of mainstream American businesses failing is more than half - prepositions are normally followed by nouns or noun phrases or gerunds. "failing" here is a verbal modifier. Wrong. "rate is more than half" here is not complete. More than half of what?

(E) While more than half of mainstream American businesses fail - First, no "unlike" comparison is required, so stop looking for a noun parallel of "the failure rate." Look for the logical comparison that the subordinate clause introduces by "while" shares very well.