This is all very helpful to me. Let me ask another question: does it cost more for the employer to use 1099 vs W2?
Costs way less for employers to do 1099 and they have way fewer obligations to you, that's why they tend to like to do it esp if they don't care about having a lot of control over what you're doing. This is also why there's this big fight over lots of workers in lower income jobs (ex. uber drivers, warehouse staff, delivery guys) being likely misclassified as 1099 instead of W2, cause they end up with all the **** and none of the benefits (self employment tax is relatively negligible at higher incomes, deductions, hugely higher solo 401k limits, etc).
1099: You're technically a contractor, that is someone they're just paying to come in and do a job for them. They basically just cut you a check per hour or percentage or whatever the calculation is, it's like if you hire a plumber to come over to do a job. You have zero job related protections.
W2: You're an employee and you're on "payroll", they have to pay their half of SS/Medicare, you can collect unemployment technically if you're fired and they often have to pay into unemployment insurance for the state, you have some, limited, protections as an employee (ex. someone sexually harasses you at work or something).
From your end, you also have to adhere to many more of the employers rules as W2, ex. as a 1099 they could technically really never make you adhere to their "employee handbook" or whatever, as you are technically not their employee. If there's BS like that in your contract, it would never hold up in court unless they'd be willing to admit you were actually an employee, re-classify you as W2 and pay back-taxes on all your income.