This is all correct but not helpful.
Are you suggesting that all aircraft entering class C/D airspace should have a ADS-B out transponder ?
Sounds like a good idea to me but I can guarantee you will have at least 5000 loud complaints due to the cost.
How do you propose to convince your fellow pilots ?
Is this adequate ?
A better option would be all aircraft to have ADS-B out/in transponders with audio alerts in all areas.
Your loud complaints just went up to 20,000 fellow pilots.
Actually probably 30,000 when they realise the Skyecho would not be accepted.
What is your plan ?