Mo. Rev. Stat. § 316.221: Exemptions.

Nonmotorized playground equipment, including but not limited to, swings, seesaws, stationary spring-mounted animal features, rider-propelled merry-go-rounds, climbers, slides, waterslides operated by a municipal or county park and recreation department, trampolines or swinging gates, whether or not located on a playground, are exempt from the provisions of sections 316.203 to 316.233.