God damned it I just can't help responding at least to this one. Note that the long answer from someone else previously was quite good too and would deserve some answer as well. But it was also quite emotional, probably since this person is involved in software industry. So I prefer wait a bit, let some water flow under the bridge, in order not to get him even more angry. And this long post deserves a long answer.

Anyway, the very fact that street lamps are financed by taxes, and not by private sector and market forces, does prove my point. There must be a reason for this, and this is precisely because very early, society understood the very particular aspect of this object. Individuals realized that it is very difficult to monopolize the use of such tools, or to charge for their use. Same for roads or bridges, as already discussed. Therefore people decided that these kind of stuffs should be public property, and that everyone should put some money to finance it, without any consideration about who does actually use it.

In case of street lamps, it is not a matter of marginal cost, but rather of question of factorization of service. Factorization is to services what marginal costs is to goods. There is some kind of duality between both concepts, and both have pretty much the same applications regarding determination of price.

This is quite interesting considerations, as far as theoretical economics is concerned. But I confess this is a bit far away from software industry.