The fierce debate over a Super Bowl commercial from Nationwide Insurance about a dead child has hit on issues of taste, emotional manipulation and brand strategy.

Yet the widely derided ad also revives a question that might have occurred to many TV viewers and radio listeners over the years: Why do car insurers advertise so much all the time?

The roster of marketers that spent up to $4.5 million for a 30-second spot on Sunday’s Super Bowl on NBC was predictably dominated by the usual car, beer, snack food and cellphone brands.

Yet Nationwide — which also ran a humorous commercial starring comedian Mindy Kaling and actor Matt Damon — was one of four insurers airing spots during the most-watched event and advertising showcase on the annual TV calendar.

Allstate Corp.’s (ALL) Esurance auto-coverage division ran spots featuring Lindsay Lohan as a kid’s “sorta mom” and “Breaking Bad” star Bryan Cranston as a “sorta pharmacist.”

Prolific advertiser GEICO, owned by Berkshire Hathaway Inc. (BRK-A, BRK-B), was represented. And Cure Auto Insurance tried to get noticed for an animated commercial playing on the deflated footballs controversy leading up to the game.

It’s not a fluke that insurers would contend for viewers’ attention with ads on Super Sunday, because the industry is among the heaviest advertisers in American business, as I discuss with Yahoo FInance's Jeff Macke in the attached video.

Getting in people's heads

According to marketing research firm Kantar Media, insurance companies spent close to $6 billion in 2014 on ads across all media, with TV accounting for the largest chunk. That's good for 10th place among all sectors. Most of the industries that spend more on advertising are branded-consumer goods makers and retailers, whose products people buy or consider buying daily.

Insurance coverage, on the other hand, is something most people only think about once or twice a year when they buy a car, have an accident, move or need to renew a policy. And few consumers are loyal to a particular brand, viewing one policy as about the same as another and choosing mostly based on cost.

Yet the infrequency of a purchase decision and slippery brand loyalty are two big reasons why insurers feel compelled to advertise constantly to remain top-of-mind for those moments when a new or renewed policy is needed.

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(This also explains why ads for mattresses, for example, are forever playing on radio and local TV. You don’t buy a new mattress often, but usually when you decide to get a new one little time is wasted. So when the time comes, the Serta and Sleepy’s people want you to recall their jingle and think of them first.)

This is why insurance providers work so hard to create characters as long-term spokespeople in (often quirky) ad campaigns. The GEICO gekko and cavemen, Progressive Corp.’s (PGR) chirpy pitchwoman Flo and Green Bay Packers' quarterback Aaron Rodgers as the straight man in State Farm ads are prominent examples.

Insurance companies have become more determined to carve out mindshare among consumers over the past decade as less business is done through insurance agents.

As technology and consumer preference have made direct buying more common, big insurers that once were content to cultivate the middlemen have had to fashion brand identities for themselves among the broad public.

This trend is really about the entire industry following the lead of GEICO. The company, which began as a government employees insurance pool, pioneered the direct sale of policies to consumers. This helped keep its overhead costs famously low, attracting Warren Buffett as an investor in the 1950s and enticing him to acquire the company outright in 1996. GEICO's lean operating-cost model allows it to plow betwen 6% and 7% of premium revenue into ad campaigns.

The industry as a whole isn't quite as aggressive as GEICO in throwing dollars at marketing messages, with big companies spending closer to 3% of premiums on advertising, according to research firm SNL Financial. But that's enough to make creating new pitchmen and catchphrases a core pursuit of insurers. These companies, after all, are little more than piles of capital, a claims-paying department and a marketing team selling policies. Expenses for claims -- especially in car insurance, where catastrophe risk is minimal -- are fairly predictable, which leaves a significant and growing source of money available for customer acquisition through branding.

That Nationwide commercial that repelled so many Super Bowl viewers, narrated by a boy who “died” in an accident, might not be imitated any time soon. But you can bet that Nationwide and all of its competitors will remain fixtures of commercial breaks for as long as TV is watched.