Automatic seat belts
Automatic seat belt in a Honda CivicSeatbelts that automatically move into position around a vehicle occupant once the adjacent door is closed and/or the engine is started were developed as a countermeasure against low usage rates of manual seat belts, particularly in the United States of America. The first car to feature Automatic Shoulder belts as standard equipment was the 1981 Toyota Cressida, but the history of the belts go back further.[23]


The 1972 Volkswagen ESVW1 Experimental Safety Vehicle presented passive seat belts.[24] Volvo tried to develop a passive three point seatbelt. In 1973 Volkswagen announced they had a functional passive seat belt.[25] The first commercial car to use automatic seat belts was the 1975 Volkswagen Rabbit.[26]

Automatic seat belts received a boost in the United States in 1977 when Brock Adams, United States Secretary of Transportation in the Carter Administration, mandated that by 1983 every new car should have either airbags or automatic seat belts.[27][28] despite strong lobbying from the auto industry.[29] Adams was attacked by Ralph Nader, who said that the 1983 deadline was too late.[30] Soon after, General Motors began offering automatic seat belts, first on the Chevrolet Chevette,[31][32] but by early 1979 the VW Rabbit and the Chevette were the only cars to offer the safety feature,[30] and GM was reporting disappointing sales.[33] By early 1978, Volkswagen had reported 90,000 Rabbits sold with automatic seat belts.[26] A study released in 1978 by the United States Department of Transportation claimed that cars with automatic seat belts had a fatality rate of .78 per 100 million miles, compared with 2.34 for cars with regular, manual belts.[34]. In 1981, Drew Lewis, the first Transportation Secretary of the Reagan Administration, influenced by studies done by the auto industry,[35] "killed"[36] the previous administration's mandate;[37] the decision was overruled in a federal appeals court the following year,[38] and then by the Supreme Court.[36] In 1984, the Reagan Administration reversed its course,[39] though in the meantime the original deadline had been extended; Elizabeth Dole, then Transportation Secretary, proposed that the two passive safety restraints be phased into vehicles gradually, from vehicle model year 1987 to vehicle model year 1990, when all vehicles would be required to have either automatic seat belts or driver side air bags.[36] Though more awkward for vehicle occupants, most manufacturers opted to use less expensive automatic belts rather than airbags during this time period.

When driver side airbags became mandatory on all passenger vehicles in model year 1994, most manufacturers stopped equipping cars with automatic seat belts. Exceptions include the 1995-1996 Ford Escort/Mercury Tracer and the Eagle Summit Wagon which had automatic safety belts along with dual airbags.

Disadvantages
Automatic belt systems generally offer inferior occupant crash protection.[40][41] In systems with belts attached to the door rather than a sturdier fixed portion of the vehicle body, a crash that causes the vehicle door to open leaves the occupant without belt protection. He or she will in that case be thrown from the vehicle and suffer greater injury or death.[41] Because many automatic belt system designs compliant with the US passive-restraint mandate did not meet the safety performance requirements of Canada—which were not weakened to accommodate automatic belts—vehicle models which had been eligible for easy importation in either direction across the US-Canada border when equipped with manual belts became ineligible for importation in either direction once the US variants got automatic belts and the Canadian versions retained manual belts. Two such models were the Dodge Spirit and Plymouth Acclaim.[42][43]

Automatic belt systems also present several operational disadvantages. Motorists who would normally wear seat belts must still fasten the manual lap belt, thus rendering redundant the automation of the shoulder belt. Those who do not fasten the lap belt wind up inadequately protected by only the shoulder belt; in a crash without a lap belt such a vehicle occupant is likely to "submarine" (be thrown forward under the shoulder belt) and be seriously injured. Motorized or door-affixed shoulder belts hinder access to the vehicle, making it difficult to enter and exit—particularly if the occupant is carrying items such as a box or a purse. Vehicle owners tend to disconnect the motorized or door-affixed shoulder belt to alleviate the nuisance of entering and exiting the vehicle, leaving only a lap belt for crash protection. Also, many automatic seat belt systems are incompatible with child safety seats, or compatible only with special modifications.

Of course they are not as safe you putting your life in the hands of a little tiny pin and a motor compared to the frame of the car. Of course its not going to be as secure.

Something that moves in the direction it is trying to stop vs a stationary object

Same reason why valves go into the cylender instead of opening out of them. If they opened out the explosion could open them but if they open in the explosion would just close them.