Condensation appears because the surface is cooler than the water vapor next to it -
Why do you have water vapor? Why do you have a cool surface (toilet lid)? The answer to one or both of those is the cause of the problem. (Either the water is too warm or the toilet is too cold.)
Hate to say this one, but it's always possible ... The supply line to the toilet could be hot water instead of cold.
If that's not it ... perhaps if the bathroom is not vented well enough - if the temperature is hot in the daytime and gets cool (rapidly) in the evening, that could be a cause (but not likely to cause a large amount of condensation. So how much condensation are you seeing?)