In my experience, most chain restaurants back of house line cooks get paid fairly low. So let's say the highest paid linecook gets 18 an hour. They work 8 hours and make $144 that day before taxes and it is added to their check. Most of the servers in the front of house would make around $150 as well but they worked less hours. (Usually 5-6 hours). They also walk with the tip money at the end of the night. Then they claim what they wish to because the government can't prove how much you made in tips. Many claim they made far less, others claim what they made for other reasons.

It is common to see servers make twice what cooks do. Which creates an atmosphere where front/back of house don't get along all the time either.

Ironically, jobs that rely on tips are some of the most inflation resistant besides CEOs, since tips are usually a percentage of the price. It's unreliable, but very well paying. Employers are also required by law to make up the difference in pay if the tipped worker does not make minimum wage with tips, though many times the employees won't do this since its incredibly common for tipped workers to not declare tips for taxes

It depends on the restaurant to the degree, but tipped positions are almost always the highest paid position.