I suspect there is a fine line between events where you get to win by submitting money (gambling), nothing of value (contest) and valuable work (tender).
The former two are heavily regulated to protect "passive participants" while the latter is materially different by virtue of participant being actively involved and is not nearly as regulated.
My humble opinion is based on similar line drawn between active and passive investments in securities laws - if one gets to profit by contributing funds but not valuable efforts it's a passive investment and the law is there to protect these people. If one gets to profit by contributing valuable effort then it's not a security and the law entrusts people to take care of themselves in these cases.
The former two are heavily regulated to protect "passive participants" while the latter is materially different by virtue of participant being actively involved and is not nearly as regulated.
My humble opinion is based on similar line drawn between active and passive investments in securities laws - if one gets to profit by contributing funds but not valuable efforts it's a passive investment and the law is there to protect these people. If one gets to profit by contributing valuable effort then it's not a security and the law entrusts people to take care of themselves in these cases.
not a legal advice. :-)