In Everton, Brighton, Arsenal and Liverpool's cases, the providers of funding ARE the shareholders.
I have a loan I took out to buy some expensive camera equipment. I'm paying the capital and a commercial rate of interest (although it's a very decent one) on that loan. The provider had to be sure I could finance that, so I had to give details of income and expenditure, which it accepted.
The thing about interest-free loans is that clubs are paying back neither the interest nor the capital. That allows them to spend that money on transfers and wages. If clubs were required to pay back shareholder loans over a maximum set period, or were required to disallow what they would have paid on repayment of capital and interest from their accounts, then that would be fairer.