Amazon.com Search, filter and sorting reslts are rigged. internet Washington

Amazon's search, filter and sorting tools do not produce accurate results. It appears as if items are presented out of order in order to favor certain manufacturers and/or suppliers over others. I have reported it to Amazon in the past and they have been able to reproduce my results but offered no explanation.

The example below is typical of the results I have found on other searches. It is NOT a onetime anomaly.

Example:
I entered "Smoke Detector" in the search field at Amazon.com

I then filtered by "Prime Eligible"
I then filtered by 4 stars or greater (reviews)
I then selected "Tools and Home Improvement" as the category
Finally I sorted by price, low to high. 

The results were smoke detectors priced in the following order:
$10.38
$7.89
$15.89
$15.04
$7.99
$10.29
$19.97
$9.47

I can only conclude that Amazon is favoring certain manufacturers and/or suppliers over another and moving their products higher on the search/sort/filter results list.