It seems as if regulating chain stores in San Francisco would be simple.

Who wants to see a giant, big-box store like Walmart in the city? Nobody, right? And how many would rather patronize a small, locally owned coffee brewer like Philz in their neighborhood rather than another generic Starbucks? Everyone, correct?

So let's ban the big chains. Problem solved.

Not so fast. As a thoughtful memo and subsequent hearing by the city's Planning Department suggests, there are subtleties to the issue, beginning with how to define a chain store, known as "formula retail." In San Francisco, that means there are 11 or more locations that all provide the same goods or services and have a uniform appearance. Walgreens drugstores are an obvious example, but even a funky place like Philz, with 14 Bay Area locations, could be considered formula.

That's where it gets tricky. Depending on the store, some neighborhoods might want a formula retail outlet. Mid-Market residents, for example, welcomed the arrival of a CVS pharmacy at Market and Seventh. CVS may be a mega-chain - it has thousands of outlets around the country - but the convenience of a neighborhood drugstore outweighed the objections.

On the other hand, the Marina is locked in an incredibly acrimonious debate over the arrival of the generally well-regarded Pet Food Express. The company is local - it started in West Portal - consistently supports animal rescue efforts, donates food to animal care groups and wants to take over a long-abandoned eyesore of a building on Lombard Street.

Vicious reaction

It also hasmore than 40 outlets. Complaining that the store would endanger small, boutique pet stores nearby, a militant group has gone ballistic. Susan Reynolds, editor in chief of the neighborhood newspaper the Marina Times, says that when she had the nerve to write that Pet Food Express would be a good fit for the Marina, the reaction was vicious.

"I was threatened," she says. "I got a really vulgar voice mail saying they were going to get rid of me. It is pretty incredible, going to this extreme for a pet store."

Or consider trendy Hayes Valley, which already has the most restrictive formula-retail rules in the city. Chain stores are absolutely banned, but district Supervisor London Breed is sponsoring an ordinance that will make the rules even stricter.

Formula retail previously was defined as having more than 11 outlets in the United States. Breed would broaden the designation to include companies with more than 11 outlets anywhere in the world. So a European clothing store with 11 stores in Spain wouldn't be allowed to open one in Hayes Valley.

"I think it just makes it more fair," says Breed's aide, Conor Johnston. "I don't see why we should be filtering domestic retailers but not international."

Many viewpoints

Everybody has an opinion. As the planning memo points out, there are eight ordinances in the pipeline, which range from restricting formula-retail food trucks to regulating outlets that are owned by a company that has been "suggested" for formula-retail inclusion.

"It is an absolute nightmare for the Planning Commission," says Ben Lazzareschi, who represents local and national retailers. "Let's not have any knee-jerk legislation. There has to be some nuance."

The Planning Department's memo amounts to an appeal for everyone to stand down, take a deep breath and look at the big picture. The goal, it says, is "to develop a series of controls that are clear, concise and easy to implement that will protect neighborhood character and provide necessary goods and services."

Good luck with that. It makes perfect sense for there to be a citywide blueprint to control and regulate formula-retail stores, but as carefully as it might be crafted, it is likely to run into that familiar San Francisco neighborhood refrain:

That sounds great for your neighborhood, but I will never support it for mine.

C.W. Nevius is a San Francisco Chronicle columnist. His columns appear Tuesday, Thursday and Saturday. E-mail: cwnevius@sfchronicle.com Twitter: @cwnevius