I think the reading books is a red herring here.
My reception-age Dd2 can read quite well (will happily read ORT Stage 8/9 with little or no support) but gets sent home with ORT stage 2 or 3, cos all the reading is assessed by a TA who, frankly, isn't the brightest spark in the fire, and hasn't thought to give dd2 something a bit more challenging.
I don't give a stuff about this atm because the reception teacher is ACE and is doing the most amazingly imaginative things with them in class. They've done a topic on senses, learnt about sweet, salty and sour (with tasting sessions) done African dancing, made African necklaces, learnt some Italian songs, built their own story corner, gone on trips to the park to collect leaves and learn to make compost etc. They are now doing a topic on animals, for which the teacher today took them to a nearby petshop where they bought (apparently) 'a bouncing rubber mouse and a dog bowl'. They don't have an actual dog in the classroom (obviously), but are apparently going to build a life-sized model dog (to go with the bowl, presumably).
This is all bonkers, in quite an inspired way, though it seems to lead into learning actual subjects -- the animals topic has inspired a wall display on size, for example. This is what I think Reception kids should be doing, and frankly I'd pay good money to have my child taught by her current teacher. And because I think what goes on in the classsroom is great, I'm really not that fussed about the reading books, as we have plenty at home left over from the older dc for her to read. If she was spending all day doing letters and numbers worksheets, and learning how to turn the pages of a book, then I would be concerned, as I think it's really demotivating for a child to be forced to spend time 'learning' stuff they can do already.
So you need to decide whether what you're dealing with is a good school that are a little lax wrt reading levels (which is fine) or a school that don't have the insight or the inspiration to do anything with the kids that exceeds their narrow understanding of the curriculum. Only you can decide that, it really isn't ultimately about reading books.