(NewsNation) — As crime surges and police resources dwindle in major cities across the country, some communities have responded by hiring private security to patrol their streets.

Over the past year, several neighborhoods in Chicago have brought in private security amid a wave of robberies and carjackings. Residents in San Francisco and Baltimore have done the same.

Many of those enhanced safety efforts are concentrated in higher-income communities where neighbors have taken it upon themselves to pay for the services.

In April, residents in Chicago’s affluent Lincoln Park neighborhood passed out flyers requesting $1,200 per household to cover the cost of a private patrol, Block Club Chicago reported at the time. Community members estimated the annual cost would be $175,000.

Chicago Mayor Lori Lightfoot has expressed dismay at the growing trend and said she doesn’t want a circumstance where public safety is only available to the wealthy.

Experts NewsNation spoke to said the move toward private security is nothing new but has accelerated in recent years.

“We’ve seen private security on a fast growth pace for 30 or more years in the United States,” said Darrel Stephens, the co-director at Florida State University’s Policing, Security Technology, and Private Security Research & Policy Institute.

Much of that growth has been concentrated in retail stores and business improvement districts, Stephens noted, but his recent research found dozens of cities have expanded the presence of private security over the last five years.

“I think it’s an extreme positive,” said Charles Nemeth. “It’s just going to get bigger and bigger.”

Nemeth, a professor and director of the Center for Criminal Justice, Law, & Ethics at Franciscan University, has been studying the impact of private policing for more than 30 years.

He rejected the notion that private patrols only benefit the wealthy and said his research found widespread success in lower-income communities as well.

Private security officers often develop better community relations than public police because they’re more “customer service-oriented,” Nemeth said.

They are also hired to protect areas where traditional law enforcement don’t want to go, he added.

Communities without private security may still benefit from their use elsewhere. If private patrols successfully deter crime, that frees up local police to focus on neighborhoods that need more attention, Stephens argued.

Local leaders in St. Louis were skeptical and expressed equity concerns after a number of upscale neighborhoods hired private patrols, according to a ProPublica report.

Dwinderlin Evans, a city alderwoman who represents some of the poorer areas of St. Louis with the highest crime rates, told ProPublica the private policing system is unfair and hurts communities that can’t afford to pay for the additional protection.

In St. Louis, a popular private firm raised its pay to exceed the local police department’s overtime rate, essentially outbidding the city for its own officers, who often moonlight as private security, ProPublica reported.

Elsewhere, however, Robert McCrie said private security officers tend to be paid less than public law enforcement and that can make it a more affordable option.

McCrie — a professor at the John Jay College of Criminal Justice — added that private security jobs can be more attractive because they tend to be lower stress than local law enforcement positions.

Private officers’ schedules are often more consistent and they’re less likely to be in harm’s way. For those reasons, private companies may be better positioned to attract workers in the coming years.

But the private sector also poses some challenges. The level of training provided to private officers varies greatly from company to company.

Regulatory oversight is limited, which means background check requirements and use of force reporting requirements tend to be more lenient. The lack of accountability mechanisms remains a primary concern.

There are also jurisdictional questions, particularly on public streets, where private security’s authority is fairly limited.

All the experts NewsNation spoke to agreed that continued collaboration between public and private law enforcement will be key moving forward.

“There’s so much for both systems (public and private) to learn from one another,” Nemeth said.