The sheer number of people that simply (out of ignorance or malice) will use these as a turn lane... parking space... what have you probably has a bit to do with it.
Tangentially related: theres a lot of distracted and shitty drivers out there. Putting something physical between you and them tends ro make people feel safer.
I'm pretty sure this study probably could have been replaced by common sense. That said - if the presence of a study results in better handling of bike lanes... good on it.
