The denial-of-service attacks against ETrade, Amazon.com, Yahoo! and several other popular commercial Web last week first were dismissed by company officials and high-tech experts as crude, unsophisticated vandalism that any 15-year-old with a mouse and a modem could pull off.

But the notion that adolescent pranksters could bring e-commerce to a halt didn’t play too well with investors and the public, especially after it was learned that the hackers could have been stopped by inexpensive, readily available software and other modest precautions. So now the officials and experts are saying the attacks were well-planned, perfectly executed and, above all, highly sophisticated.

In recent weeks, hundreds of thousands of credit card numbers and account passwords have been stolen from several online retailers. In each case, the retailers failed to encode the card numbers. Once the hackers — whether mischievous 15-year-olds or hardened career criminals — got past the flimsy protective firewall, the numbers and accounts were there for the taking.

What these two situations have in common is that the e-businesses knew of the protective measures available and rejected their use. Filtering software and encryption slow Web pages down — by just a few seconds. But, when it comes to Internet businesses, speed is what counts, unlike at responsible, real-world businesses, which slow down long enough to provide customers with security for their financial information.

The Internet industry has reacted to these crimes by quickly and resolutely making it someone else’s problem. Credit-card holders are advised to straighten things out with their banks. Law-enforcement is urged to get busy tracking down the hackers, Congress is told it needs to enact stiffer penalties.

This shifting of blame and responsibility is no surprise coming from an industry that has always held itself immune from the cares of the workaday world. The collection of sales taxes, the shielding of children from pornography, the protection of intellectual property and the enforcement of copyright laws all are too mundane for the high-fliers of cyberspace. It’s bad that an industry so vital to the economy is vulnerable to the pranks of irresponsible teens with no respect for the property of others. It’s worse that the industry seems to be run by them.

Even worse is that no one in government appears willing to call the Internet industry to task for its negligence and sloppiness. The FBI is on the case, even asking for the public’s help. Congress can’t wait to get tough. President Clinton reacts to this severe breach of the public trust by observing, “From the beginning of time, where things of value are stored, people with bad motives will try to get to those things.” The difference is that this time, the people entrusted with storing those things of value just don’t want to be bothered with locking them up.