Pushbikes are practical if it`s not raining, night time, if you don`t have to carry load and don`t impact on other traffic. Also good for undeveloped countries, and countries with a huge supply of available drugs, like Amsterdam.
It's probably none of my business, but you swerve in and out of the opposite traffic lane much faster when passing a slow cyclist than if you were passing a faster car. The undivided lanes are painted in mind of passing another car wyich travels at a posted speed limit. Naturally, some motorists will now be able to cause crashes and face lesser charges if they say there was a would be cyclist in the area. Moreover, leaving 1.5 meters for a cyclist, that's a lot of space on the road. Should be something like 0.5-1 meters.
Obviously not telling you anything you don`t know, but to mix vehicles of differing speeds, even under "ideal" conditions, is asking for trouble. I personally know two people who have been involved in pushbike / car accidents where the bike rider was killed. Not nice.
Mate, you seriously need to check out Amsterdam for yourself. You will discover that there are special bike paths for bikes, and very few bikes share the roads over there with cars. The only reason why bikes share the roads with cars over here, is because our politicians cannot afford to build special bike paths to keep bike riders safe like in Amsterdam.
I agree on Amsterdam, however in every smaller town in the Netherlands roads are shared between bikes and cars. The same applies for the vast majority of Europe, whether we are talking France, Austria, Switzerland, Germany and so on. I do agree that bike lanes are the safest option, but sometimes due to confined spaces they are not always possible. Cheerio