According to the Pattaya Mail (which may not be a very reliable source), 45+45 was proposed by the Tourist Authority of Thailand. It's a shame the proposal was not adopted.
https://www.pattayamail.com/latestnews/news/prior-holiday-visas-to-visit-thailand-are-becoming-redundant-406232
"The Tourist Authority of Thailand is pressurizing the government to allow most vacationing foreigners to visit Thailand for up to three months without obtaining a visa from their local Thai embassy abroad. Visitors from 64 countries (including Brits, Russians, Australians, Americans and most mainland Europeans) are already visa-exempt. They obtain 30 days free-of-charge on arrival which can be extended for a further month at Thai immigration on payment of 1,900 baht. If the Thai Cabinet, as expected, accepts the proposal, these periods would become 45-plus-45 days for a total of three months."