Search results are weighted against what people who searched for similar things clicked on, more clicks higher it is in the results. When 4.0 came out 3.0 had already been around for years and 90% of people who searched for the product clicked on 3.0 and almost no one has clicked on 2.0 since 3.0 came out, so the results have 3.0 on top.
>causing me to purchase the wrong thing
That really is your own fault and has nothing to do with Amazon or Google, read the description before buying.
Search results are weighted against what people who searched for similar things clicked on, more clicks higher it is in the results. When 4.0 came out 3.0 had already been around for years and 90% of people who searched for the product clicked on 3.0 and almost no one has clicked on 2.0 since 3.0 came out, so the results have 3.0 on top.
>causing me to purchase the wrong thing
That really is your own fault and has nothing to do with Amazon or Google, read the description before buying.