I think the Internet has misled you a bit. There is a large difference between ta and teachers salary but there is also a difference in expectation and responsibilities. Wherever I have worked as a teacher, the TAs have not been expected to arrive earlier or stay later than the school day. The work they do with the children is planned by the teacher and it is the teachers responsibilty to make sure the work is suitable for the children's ability. They are accountable to parents, management and governors for the progress of the children and also take on responsibilty for leading one or more curriculum areas.
Teachers have a degree and have either spent a significant part of their degree achieving qualified status, or have done the equivalent of a years full time, postgraduate training to become a qualified teacher, plus then have to complete a further year of NQT training and assessment.
None of this is intended to belittle the role of TAs, merely to say that the two jobs are different. There are schos where unfair expectations are placed on TAs but this is by no means the norm.
Finally, teachers might technically earn £150 per teaching day, but when this is spread across the year, it is significantly less. TA contracts are increasingly term time only, which is unfair in many ways, but it isn't a myth that teachers spend significant portions of the holidays planning.
All that said, I am a teacher considering becoming a TA. Why? Because I do t want all the extra stuff that comes with a teachers job. I want to be there for my children in the evening and leave the job at school.