It’s 5% per year because you are charged interest on some schedule based on how much you have paid off. 5% is a rate, 93% is a total amount and it only applies if you pay the whole mortgage off at exactly the prescribed rate. Many banks’ mortgage calculators will show you the total amount paid anyway so it’s not like they’re hiding it.

Your point seems to be basically that because you can’t do the maths, the mortgage is misleading. That is maybe a fair argument in some cases with financial products. Investment banks are notorious for obscuring the true cost of deals with complicated maths. However this doesn’t seem like a case of that. If the interest rate is 5% APR and you are free to pay it off as fast or as slowly as you like within some bounds, for example, it is absolutely essential that you understand what a 5% rate means to know how the mortgage works.

edit: not to mention that 5% is already a contrived figure not representative of how the interest is actually applied, designed to make it easier for you to understand what you’re charged. Your interest is probably calculated monthly or daily, not yearly. They could present you a nice hypothetical yearly figure, or a nice just-as-hypothetical 93% three-year figure. What’s the difference? Neither of them are real. Your interest is charged monthly, so they’re equally fake and misleading.