I guess the non corrosion proofed aircraft was cheaper to produce and sell
Back in the day corrosion proofing on the Cessna various was an optional extra. Probably only gone for by fastidious owners and those operating on floats. The non corrosion proofed 150 I learnt to fly on in '62 is still going gangbusters with no visible corrosion issues, and lived by the ocean for a time. No zinc chromating Jay. Aircraft had minimal exterior painting in the early days, plenty of nice shiny bare metal externally. This being rather typical.
