These same issues must affect Pipers etc.
No. Other issues may affect Piper and other manufacturers, but the big hitters in the Cessna SIDs programme are unique Cessna design issues.
Its worth the reality check that only Cessna has created a SID programme. Piper hasn't. Beechcraft hasn't. Mooney hasn't. Socata hasn't. Cirrus hasn't (the oldest Cirrus are now 16 years old). Aviat hasn't. Maule hasn't. Gipps Aero hasn't (oldest GA8's are 18 years old), Thrush hasn't. Air Tractor hasn't. Piaggio hasn't. American Champion hasn't.
Its also worth noting that Cessna did not intend the SIDs programme be mandatory.
The real question that our regulators should answer is "where is the data to support this requirement?". How long have we been collecting accident & incident data? If there is a smoking gun, there is no excuse for not knowing where it is.