There are valid reasons for government involvement here. The biggest is to protect consumers from being taken advantage of by the equipment manufacturers and the market forces. Same reason as why we have laws against tricking dumb people out of their life savings all sorts of other unfair trade practices.
The manufactures, and government safety standards groups know a lot more about what is safe and what is not than any individual buyer (they have all the stats from all the lawsuits they get hit with). They also know how much the safety equipment costs to add to the product (ROPs, belt, interlock, etc). Without some kind of regulations, there most certainly would be manufacturers who would make the decision that selling the cheapest product is more important to their success than selling a safe product. Pretty soon, price competition would make it impossible for any manufacturer to offer safety equipment. Even if they did, it would be an expensive option that was a hassle to order, and most purchasers would be very tempted to skip it.
Meanwhile, the low-price manufacturers would have a huge incentive to lie about how safe the equipment is even without the additional safety equipment.
By having government regulations, it sets a reasonable minimum level of safety so that the manufacturers can compete on real features and cost reductions, and not compete on how good their marketing is at making you believe something is safe enough when for a few bucks more, it could be a lot safer. Then, smart people who know the value of safety over a few bucks can be assured of even having that choice available in the market.
If pure market forces are allowed to rule, unfortunately, most people make the poor decision to sacrifice the value of human lives (their own, or others) at much too low of a price.