You're just misunderstanding the parent post. He mentioned that the Tesla is tax beneficial because it's electric and the Mercedes selling at around the same price isn't because of its weight.
These two statements are not mutually exclusive.
In The Netherlands cars are taxed on multiple factors[1] including CO^2 emission, type, and very significantly on weight.
In Tesla's case the weight is being heavily offset by the lack of CO^2 emissions, whereas the Mercedes gets all the taxes of a normal gasoline car and the weight tax on top of that.
1. http://www.expatax.nl/kb/article/how-much-road-tax-will-i-ha...
but, at least in the Netherlands, they are taxed way differently. I also heard people that leased them, and in the end the price over a few years is comparable to a €30K car, not another €100K car.
Yes, I understand that. I just pointed out that the reason is not that the Mercedes is heavy and the Tesla light.
Presumably this comes from the fuel efficiency per manufacturer fleet, which tends to discourage heavier vehicles as they usually are less fuel efficient. So heavier, more polluting vehicle counts against you not strictly heavier.
The weights of the Tesla Model S and the Mercedea Class S are pretty much identical.