For years, regulators and privacy advocates around the world blasted Google for collecting e-mails, text messages and other personal data from residential WiFi networks as its Street View cars roamed through neighborhoods to map out and photograph roads.

Federal investigators launched two probes. The collective results of their efforts: a pledge by Google to stop the practice — and a $25,000 fine, or .001 percent of what the search giant earns in a single day.

The light touch frustrated some lawmakers. Rep. Edward J. Markey (D-Mass.) called the penalty a “slap on the wrist” and said a deeper investigation may be needed.

“Google’s Street View cars drove right over consumers’ personal privacy while cruising city streets and neighborhoods,” Markey said in a statement. “Consumers saw their Wi-Fi morph into ‘Spy-Fi’. ”

But regulators say the real problem lies in the country’s antiquated laws, which have not kept pace with the tech industry’s advances.

The Federal Communications Commission, which imposed the fine on Google this weekend, said that “there is not clear precedent” for applying the nation’s eavesdropping laws to WiFi networks.

The federal investigations highlight the government’s difficulty in protecting consumers within the constraints of current law as tech companies search for money-making endeavors that bore into personal lives, some consumer advocates said.

“What this shows, and what the FCC has recognized, is that Congress needs to update the [wiretapping] law and make sure it’s current in light of technology that we use today,” said Marcia Hofmann, a senior staff attorney at the Electronic Frontier Foundation.

In this case, Google also did what it could to hinder the FCC investigation, the agency said. The company failed to provide documents in a timely fashion, and the Google engineer who developed the streetcar software invoked his Fifth Amendment rights when regulators tried to question him.

Concerns about Google’s Street View program — an ambitious mapping plan designed to offer 360-degree photos of street scenes all over the world — surfaced in early 2010 when German authorities asserted that Google’s cars were collecting personal Internet content as they drove past houses with WiFi networks that were not password-protected.

Google initially denied the claim. Months later, after hiring a consultant to look into the matter, the company acknowledged that it had collected the data by mistake. The company also said that it had removed the equipment in its cars in all countries.

In 2010, the Federal Trade Commission closed an investigation of the matter after Google assured the agency that type of data collection was a mistake that would not be repeated. The company said the engineer responsible for the program included unauthorized coding that captured data from U.S. households between January 2008 and April 2010.

Regulators said they have no evidence that Google did anything with the personal data.

Some activists say that the agencies lack the political will to take on Google and that various regulatory bodies around the globe have taken more aggressive action.

Even though the engineer at the center of the controversy isn’t talking, regulators could have subpoenaed documents, said Marc Rotenberg, president of the Electronic Privacy Information Center, which asked the FCC to investigate.

“The federal wiretap law is one of the strongest laws in the United States,” said Rotenberg, who is asking the Justice Department to launch an investigation. “If any individual were to intercept and download private communications of someone else from their home, they would be looking at a wiretap indictment.”

Meanwhile, a multi-state investigation initiated by then-Connecticut Attorney General Richard Blumenthal continues. Blumenthal, who is now a U.S. senator, said he’s troubled by the FCC’s recent action.

“Google’s failure to initially cooperate undermines their claim and federal agencies’ conclusions that they violated no federal laws,” Blumenthal said in a statement. He said he would continue his effort to update the law.

Google plans to file a formal response to the FCC decision within 30 days. For now, the company said it “provided all the materials the regulators felt they needed to conclude their investigation and we were not found to have violated any laws.”