I lived in Boston/Cambridge/Somerville/JP/Brighton etc etc for nearly a decade from mid 90's to early 2000's, half of it as a bike messenger and lived all you describe daily, 365. Hundreds of accounts in that time that do not paint a very warm picture of American "city" living during this era. For every stupid thing someone has done to or near me in a car I have seen an equally shocking occurrence on a bike. Maybe not daily but hooo boy, people are always stupid traveling in any mode of transportation. I don't think anything will change re: bike barriers unless the auto is completely removed from the picture like in various EU cities. EVEN THEN, people will still people on bikes. Count on it...