TA salary should not be based in any way on what you (or any teacher) thinks is ‘fair’ and befitting their lower than you status. Apart from anything, many ta’s are highly educated and qualified. The op is a qualified teacher. My sons ta has a doctorate in astrophysics (I’m not sure you get any more ‘subject expertise’)
They should be paid according to the value of the work they do- many children with SEN could not be in school without them, they are relied on to make up ratios for everything, they plan and deliver lessons when teachers are doing other things, and generally make the school day actually possible.
30 five year olds and one adult, who has to fasten every shoe lace, zip every coat, clean up every spilt water bottle, clean every scraped knee, answer every question, deal with every meltdown from a child with asd, supervise every toilet break, take every ill child to reception, listen to every child read, sign every reading diary, make every classroom display, find every lost bit of equipment, tidy the classroom then set up the next activity, deal with every child with adhd who jumps about all over the place, speak to every concerned parent, put letters in every book bag, supervise every hand wash etc etc etc- all while teaching to a standard to please SLT and ofsted?
Without ta’s schools literally couldn’t function, and their pay should reflect that.