More the plunge in O&G prices during the 1980s. Coal, oil, and natural gas got incredibly cheap under Reagan after the US cut sweetheart deals with the Saudis. Nuclear has huge upfront development costs, while oil, gas, and coal are very cheap to start up and run incredibly high margins.

Lobbying and activism had very little impact, as evidenced by the campaigns against coal waste and gas flaring and strip mining that all fell flat.