Translators and agencies are a very much like tradespeople.
Big Dave down the road says he is happy to redecorate your double bedroom for £450 all in.
Elite Decorators come in at £250 a day times 5 days plus cost of paint, so probably £1,500.
Big Dave comes to your place with a bucket of paint, old trainers and no protection sheet. Elite will painstakingly fill in all cracks, rub them down, carefully lay masking tape and keep the site immaculate.
You have got the idea. Translation works in the same way. Some linguists will research the current terminology, polish the text so it reads like an original. Some other will work for agencies paying offering very low rates and have to work unsustainable volumes to survive.
BabelOn-line believe that if it is worth translating, it is worth translating well. We will try to help you reduce the volumes to translate and will offer competitive rates.