I am probably the leading accident investigator over here for small and fast craft accidents.
If the driver is proven clear on a police breathaliser test, then that is that.
If I were the driver, I would be addressing accusations of drunk driving made against me by the police, the media or posters in forums through my legal representative !
If there is a history of collisions with the jetty because of poor nav mark lighting then the relevant authorites should take heed and address the issue. Over here, an acident report citing this a cause factor woyld result in immediate action by the relevant authorities.
Having said that, surely a properly prepared passage plan would have led the skipper of the craft to expect a major obstacle such as a pier whether lit or not and to drive at an appropriate speed and degree of caution in the vicnity?
If in doubt, stop and check !
Every accident that you walk away from should be considered a learning experience !