explaining that elementary type copy and storage references do not in Solidity

mVoting.sol

pragma solidity ^0.8.0;

contract Voting {

    uint256 votesCount;

    struct Vote {
        bool hasVoted;
        string vote;
    }

    mapping(address => Vote) votes;
    
    // ; opcodes
    // PUSH1 00 ; push number 0 on the stack (for slot 0)
    // SLOAD    ; load value at storage slot 0 (= `votesCount`)
    function getVotesCount() public view returns (uint256) {
        
        uint256 currentVotesCount = votesCount;
        return currentVotesCount;
    }

    // ; opcodes
    // PUSH1 00
    // PUSH1 01 ; push 1 on the stack (storage slot nb 1 for `votes`)
    // PUSH1 00
    // CALLER
    // PUSH20 ffffffffffffffffffffffffffffffffffffffff
    // AND
    // PUSH20 ffffffffffffffffffffffffffffffffffffffff
    // AND
    // DUP2
    // MSTORE
    // PUSH1 20
    // ADD
    // SWAP1
    // DUP2
    // MSTORE
    // PUSH1 20
    // ADD
    // PUSH1 00
    // SHA3
    // SWAP1
    // POP
    // PUSH1 01 ; push `true` for `hasVoted` onto the stack
    // DUP2
    // PUSH1 00
    // ADD
    // PUSH1 00
    // PUSH2 0100
    // EXP
    // DUP2
    // SLOAD  ; load the value located at the storage reference 
    // DUP2
    // PUSH1 ff
    // MUL
    // NOT
    // AND
    // SWAP1
    // DUP4
    // ISZERO
    // ISZERO
    // MUL
    // OR
    // SWAP1
    // SSTORE ; update the storage by marking it `hasVoted`
    function hasVoted() public {
        Vote storage callerVoteDetails = votes[msg.sender];
        callerVoteDetails.hasVoted = true;
    }

}