Suzanne Horton has spent 20 years working in primary schools and has had experience teaching all year groups across the primary age phase.
I read the above in one of the Google books about grammar in primary school.

https://books.google.co.uk/books?id=J2KEAwAAQBAJ&printsec=frontcover&dq=Suzanne +horton+grammar+book&hl=en&sa=X&ved=0ahUKEwjvm6KQ1_fpAhWCi1wKHe6_CH4Q6AEIJTAA#v=onepage&q=Suzanne%20horton%20grammar%20book&f=false
It's after the contents section and under the heading "The authors"
please explain the use of "has had experience" and "has spent 20 years" in the given context.
why the simple past tense doesn't make sense in place of "has spent 20" and "has had".
I know it's the present perfect but want to know the difference between the two tenses in the above.

The present perfect connects her work and experience with the present (as of the time of writing), suggesting that it has continued up until the present (or recent past) and/or has contributed to her present abilities or knowledge.

The simple past would make her work and experience seem more confined to the past and less relevant now, e.g. because she is retired, dead, now doing other things.


The Present Perfect suggests she is still working there and still getting experience.

The Simple Past tells us nothing about her present situation. It implies that she is not doing this at present.

eg Maybe she retired. eg Maybe she died.