Why can't the server get the client MAC address, like the client IP?

Question

From what I know, all the MAC addresses that the packet gone through are in the packet. This is because that each packet that goes in a certain path, should also be returned

Answer 1

The simple difference is: IP addresses are end to end adresses (in an IP packet of course), whereas MAC adresses are only used hop by hop. Additionally the underlying MAC protocol could change on every hop, without knowledge of the client, therefore the client may not even understand all the adresses along the way of its IP packet.