Yeah, and keep in mind most of those houses where merchant houses where trade happened at the time so there probably was a lot of loading and unloading going on everywhere.
Although, given the current-day Dutch attitude to bike helmets I wouldn't be surprised if our ancestors were just being stubborn too, haha.
Most likely the latter. Thousands of bikes, a hundred people, and more than thirty cars fall in to Amsterdam canals each year. "What to do if your car falls in the water" is part of driver's ed.