Desktop clients have been delivering business logic to clients for a very long time with few problems. Web powered apps are similar. The issues involve protecting data stored in the cloud, communicating over secure channels and client security. JavaScript powered applications running in a browser have many security considerations, but they're manageable if you have security aware engineers building your application. Knowing about OWASP[1] helps.
Are there any e-commerce platforms that trust the client to do all the business logic for an order/checkout? If so how do they prevent client side tampering with the business logic without redoing it on the server side?
It seems a naive proposal at best to suggest the client would get business logic in lieu of the server. Typically clients need to assist users and they do that by use of business logic based validations and constraints.
Oh I agree but the GP seemed to indicate that trusting client side logic is a solved problem for web apps. I was curious if he had any sort of examples since it doesn't seem to be something related to the issues he listed.
[1] https://www.owasp.org/index.php/Main_Page