I am so sure, because it is logical. It would not make any sense whatsoever to sell a HP Care pack that would only cover the cost of parts and labour to service a defective printer, if the problem was a software driver or supplemental software distributed WITH the printer by the manufacturer.
However, to determine if I was correct or not, I called HP's Care Pack Designjet Support Team, and they absolutely confirmed exactly what I said. The Care Pack covers hardware and software issues for the product the HP Care Pack covers. They specified they would not offer support for say, Adobe products, but they would offer support for the HP printer driver and APS software.
If you would rather let a local repair shop play with your printer, by all means, give them your money. But for my money, I'd rather have the designers and manufacturer fix my equipment should a problem arise.
As far as them providing the exact same hardware support as HP, get it in writing. And what does a yearly cleaning/maintenance of the printer mean? They use a can of air to blow out dust particles and oil the print-head carriage?
I'm not trying to be argumentative or faceitious. I think you're comparing apples to oranges in terms of the service and support the local repair shop says they provide. They just wouldn't have the backing, the depth of knowledge or the commitment to solving potential problems.