I think the McD's example is actually the rare version because it saw a judgment. Most often, when big corporations have done wrong, they settle early to avoid the bad press. ...but that also assumes that the plaintiff has deep enough pockets or a lawyer willing to push the case.
Just to add a little background, I forgot about the specifics of the McDonalds case so I checked out Wikipedia. So a 79 yr old woman that was in the passenger seat of her grandson's car purchased a coffee at the drive thru. The grandson reportedly pulled over so the woman could add cream and sugar to the coffee. The cup was between her legs when she accidentally spilled it all over her thighs causing the burns which resulted in her hospitalization. The woman asked for $20,000 from McDonalds to cover $10,500 of expenses she had already incurred, with the additional amount to cover pain, suffering, and future medical costs. McDonalds rejected her claim and offered her $800. Therefore, the lady contacted a lawyer and the lawsuit went to court. Although the jury awarded over $2.5 million, the Judge reduced the amount to $640,000.00. McDonalds appealed and there was an undisclosed settlement of something less than $600,000. Also, the jury placed 80% of the blame on McD's and 20% on the customer. Furthermore, the cups at that time DID already say contents are hot. It came down to the fact McD's served their coffee about 40 degrees hotter than other establishments. Another note, the punitive nature of the $2.5M verdict amounted to about 2 days worth of coffee sales at McD's.
IMO McD's either didn't take the time to fully investigate the claim (if they did they probably could have just had the insurance company payout), or they felt they could just bully this person and they would go away with nothing. And/or they just didn't want to pay because it might inspire other lawsuits. I imagine their legal fees just to respond to the lawsuit were way more than $20K originally requested by the customer.