The whole concept of liability is interpreted quite differently in Europe. Whereas Americans appear to treat everyone as ignorant and uneducated, Europeans tend to view people as rational and aware individuals. When you buy a product or service in Europe, the onus is on you to know how to use it properly, to know what can go wrong with it if you use it incorrectly, how it can harm you or others, etc. etc.
Essentially you have to be informed. Much like you can't say you did not know something was against the law in America, you can't say you did not know the object or service could harm you in this or that way in Europe. It is your responsibility to check out the object or service beforehand, to read up and learn about it, to make sure it meets your needs, and to be aware of its pitfalls and dangers, including those that are not obvious. Additionally all the risk in using the object or the service is yours.
It is your responsibility to know you are fit for bike racing and to know all the dangers you are exposing yourself to when racing. Belgian racers need a yearly medical checkup to get their license. As a foreigner it is up to you to decide what you need or want. By entering a race, you are assuming all the risks associated with racing, even those risks that you may not know about.
The immediate corollary is that most items come without tons of warning labels and self-evident instructions, and most activities can be enjoyed without filling out 50+ pages of paperwork. The additional advantage is that most services are a whole lot cheaper too since nobody has to take out millions of dollars worth of liability insurance.
When you send your 15 yr old to Belgium to race, he or she will be able to enter any race by just showing their license, permission letter and kalenderkaart. All they will have to do is pay the fee and sign their name. Nobody else has to sign anything and there are no forms to fill out either. There are no liability forms, medical permission forms, or any other forms. No adults need to be present and usually none are other than the officials.
The drawback -if you can call it that- is that you won't be able to sue if something goes wrong, and if you do sue and your lawsuit does not get thrown out, your chances of winning are virtually non-existent. Furthermore, even if you were to somehow miraculously win your suit, your compensation will be hardly worth the effort you put in. Pain and suffering is not part of it, and neither are punitive damages. All payments for medical bills will be severely capped.
The same applies to medical malpractice. Malpractice suits are almost unheard of in Belgium. While you may be able to get your cleaning bill paid when your doctor spills blood over your new jacket, taking that same doctor to court for mistreating you is a loosing proposition. Your chances for success are less than your chances of winning the California lottery.
That said, medical care is every bit as good in Belgium as it is in the US. And a whole lot cheaper too. That much I can vouch for as a knowledgeable party.
There is one other medical twist that you need to be aware of before going or sending your kid. In Belgium, trained personnel must attend to medical emergencies. If they don't they can lose their license and cases like that do happen. If a doctor or nurse witnesses an accident, they must intervene. There is no "consent to treat" here. You will be treated and nobody will be able to turn you away for any reason. Nobody will be able to intervene and stop them either.
Not surprisingly, first responders are covered by blanket good Samaritan laws. Whatever anyone does to help you in an emergency -as long as there is no foul play- is protected from liability, even if the first responders make a mistake. While this may sound draconian, all in all it is tremendously beneficial for everyone involved.
Note that many US healthcare policies won't pay for charges incurred outside the service area, let alone in Europe. Always make sure you have emergency medical coverage when traveling abroad. You enjoy some coverage through USA cycling and your racing license but it is always wise to make sure this insurance will meet your needs, and to buy additional insurance if necessary.