There are probably many people who don't have the luxury of baseboards, tables etc, who will run their trains on carpet, so Sam's Trains caters for them.
As Sean says, testing under difficult conditions like carpet is probably fairer than testing under ideal conditions.
Reading the comments under the various YT videos, people seem absolutely enthralled with the 55's; the quality, the innovation, the features and the value.
I guess that none of them had experienced the IRM A's!
One recurring theme in the reviews and comments is how Accurascale have set the bar for other to follow.