"as this individual does not have a business to speak of and does it have to be subject to SE taxes."

Providing services as an independent contractor would be subject to SE tax. That's what happens when you do work.

"could have issued her a 1099-MISC as other income or paid her via W-2 wages"

Was she performing, or dumping trash, or cooking, or? It is common to get paid 1099-NEC for performing, and issued when the payment(s) from that one entity to this taxpayer reaches $600 or more. That's how the IRS requires it.

The only time I've seen a band get caught in "shoulda been hired as employees" was when Willie Nelson's band played a fair in Montana, and the State tried to claim worker misclassification. The State lost this argument.

If your taxpayer showed up for an event and essentially provided everything it took for them to do whatever was done, that would be 1099-NEC income. That would be SE. Having little to no expenses would be the ideal situation. It does go on Sched C. You would have to know if the mileage qualifies as business or as commuting to the job site. Example: out of town overnight and requiring a rest period, away from home = business miles as part of business travel.

If you want to claim worker misclassification, because this person should have been classified as an employee, that is certainly an option:

https://www.dol.gov/agencies/whd/flsa/misclassification