A lot of this comes down to A/B testing. Once people have found a solution that converts some number of customers, it's hard to take risks. There are alternative designs, but it's safest to just go with what is known. In some cases, the familiarity is helpful for users, but there is no denying that it can be boring. These are the unfortunate constraints that many talented people have to work in.
Given how badly I’ve seen a/b tests being conducted at multiple companies, I’m not sure I’d assume anything from competitors works particularly well.
I can guarantee from my experience that most internet marketing practices are determined by the blind leading the blind.
Certainly my experience as well.
Would concur 100% on "blind leading the blind" here.