The car park should have CCTV, which hopefully allow the investigators to establish the facts leading to the fire.
UK fire and building regulations are based first on life safety, hence no sprinklers and only minimum 15 minutes fire protection in car parks of this height. It is expected that allows fire service intervention before the fire spreads, which failed this time and a few times before.
Sprinklers, fire pumps, water supplies and their maintenance just adds costs, which developers don’t want.
Many years ago, many large UK DIY stores and supermarkets burnt down. These had no sprinklers and often no fire insurance. Sprinklers only were installed after the companies could no longer continue to write off the costs and then they had to get insurance. The insurance companies then required sprinklers to reduce the risk of money losses.
Balance between life safety (fire/building regs) and property protection (insurance), cost making the final decision.