actually it's totally opposite, imo

option 1 - contract worker - you need to have some real skills. you need to finish the work load on time and it is stressful. nobody cares about your life, political views, family, etc. they just want you to get the job done.

option 2 - permanent position - more people at interview indicates the group wanted to watch you if you can fit in, not because of your skills, but rather personalities. this is the place "估計去了活不會太累，跟著大夥一起談談理解，忽悠忽悠，胡天胡地的概率比較大".

OP seems only care about monetary comparison. She should check the dictionary and look for a word called "overhead" per employee. Check what benefit included in it. I am sure the $10-20k won't compensate for the pure income difference between the two options.

So it's a no brainer to pick 2, imo.