I wonder if this is completely true. There were quite a few electric vehicles around 1900 while cars with diesel engines were rather uncommon at that point in time.
Most electric car companies were bankrupt before 1920, however I would be surprised if not some application survived, making your statement technically correct.
So there may have been more electric cars in 1900 but not more electric car registrations
But in the grand scheme of things, we've never had more horseless cars in circulation than today, in 2020. The electric ratios of 1900 we're talking about are rounding errors by comparison to today.
But what I find fascinating most of all that it's been a hundred years and we're having similar conversations, again. Hundred years ago there were massive arguments about traffic pollution in the cities. However, it revolved around horseshit in the streets. People welcomed the newfangled gas belching cars and hailed them as the clean wave of the future.