The government has a very different role in this to the various lobby groups on the leave and remain sides. Having foolishly allowed the referendum, it was perfectly order, as the executive, to let the electorate know what their position was. After all, in theory they knew better than anyone else* what the implications of the referendum decision were likely to be. I can't see any good reason for bringing in the rather modest (in my opinion) sum of money they spent on letting us know their position, and that expenditure should not be set alongside the remain campaign's expenditure. The government is not a lobby group.

*Words chosen advisedly. :-)