Sorry to be pedantic about Motability scheme and mobility allowance, but those who get so frothed often do so, partly because of getting different schemes and allowances mixed up. (as well as just nastiness)
You can't use the Motability Scheme (a charity - not funded by taxpayers) to BUY a top end or otherwise, car, and then get hand controls fitted.
You can buy a top end car, and use a mobility allowance (PIP) to get hand controls fitted.
Or if you have higher rate mobility allowance (PIP) you can put down a substantial additional payment (AD) which is non refundable, and trade in the mobility allowance in it's entirety, to LEASE a higher end (or otherwise) Motabillity car, for 3 to 5 years from the charity, and it will be supplied with hand controls, if that's the assessed adaption need.
The charity keeps the additional payment, and needs to sell on the car before it devalues too much, and that's the optimal second hand selling point for a new car. Adaptations are usually but not always, removed and reused.
When it's shown to people that it costs them as taxpayers exactly the same for the exchanged allowance for a disabled person to have a top end Motability scheme charity car, as it does for the cheapest possible one, they still insist either the disabled should only have access to cheaper cars, or that PIP should be means tested because disabled people shouldn't be assisted unless they're poverty stricken and kept out of the jobs market, etc.
(Disclaimer: I have neither Motability scheme car or electric wheelchair - old banger and manual wheelchair only)
They froth because they feel those of us who need assistance to be able to work, earn and pay tax, shouldn't be considered 'proper' taxpayers like them, shouldn't benefit from working beyond not being on Universal Credit, and it's their business because they're taxpayers.