Fewer big companies are owned by the original owner, and maybe own by new owners which mostly care about making money even if they ruin a company reputation by saving money by using poorer quality parts, lowly paid workers, or features which very few people wanted.
Many electronics explosions are from big brands like Samsung and Apple according to News stories on the local news, and news websites.
A Different Samsung Smartphone Exploded In Man's Hands
Apple looking into reports iPhone 7 exploded while owner was asleep
When big phone companies like Apple and Samsung make many millions of smartphones per year, there is a chance that a few smartphones will explode or catch on fire because the factory worker assembling the smartphone made a mistake, or forgot to install a safety device to prevent battery explosions. A wire or part inside the smartphone may of malfunction which accidentally cause the phone to catch on fire.
The chance of being a victim of an electronics explosion is rare because there is usually an electronics safety worker which inspects products to see they are safe, and not broken before shipping them to the public. But, there is always a chance that the safety inspector may not be properly trained, careless, having a bad day, and did not stop unsafe smartphones from being shipped to a store.