Health insurance in particular is an item that not only doesn't scale well with income, it doesn't even always share the same cost and benefit for W2 employees making exactly the same hourly wage working for the exact same employer. So why should you apply a flat 2x multiplier to your W2 salary? Here's an example:
In 2023 the average employer contribution for all health care plans (single coverage) was $7,034. For family coverage it was $17,393.
If we say our W2 person has 2 weeks of vacation and 8 holidays, then these health care contributions are earned over 1,936 hours. So health care for a W2 employee costs the employer $3.63 per hour for a single employee, and $8.98 per hour for an employee with a family. That could be anywhere from 7% to 18% for an employee making $50 an hour. It could be a 14% to 36% for an employee making $25 an hour. Perhaps the employer has employees using a spouse's health insurance. In that case, there is a 0% cost, but the employer can't well agree to pay that person more upfront because they won't be able to adjust the pay if their spouse loses coverage.
But that's the cost to the employer. The benefit to the employee can be different. For example, to the married employee with a working spouse, it's only the difference in cost between the offered insurance and what can be purchased from their spouse's employer. To lower-income workers, it might be the difference between the offered insurance and that available on the marketplace if only the employer didn't offer insurance. This is still all through the W2 structure.