Signatures aren't secure, but that misses the point. In this instance the signatures are used as evidence that those transfers were sent, reviewed, and approved by a judge. Had it been done a verifiable document trail would exist.
In this instance when it was discovered the signatures were faked (or cloned), they could go look at the document trail and it was quickly discovered that none existed.
People will likely suggest other alternatives to signatures, like a unique serial number, but ultimately if people aren't verifying the document trail in the signature case, they won't verify it with a unique ID case, or most other clever means you can come up with (e.g. QR code, some kind of complex crypo method, etc).
If it is a document that allows faxing and photocopying, and nobody is taking the time to verify the authenticity of it, there are no more secure systems you can create. Things like holograms, specialist paper inlays, seals, etc can easily be faked during fax/copy. Signatures are about as good/bad as anything else.
The legal system is built on trust, verify, and punish.
In this instance when it was discovered the signatures were faked (or cloned), they could go look at the document trail and it was quickly discovered that none existed.
People will likely suggest other alternatives to signatures, like a unique serial number, but ultimately if people aren't verifying the document trail in the signature case, they won't verify it with a unique ID case, or most other clever means you can come up with (e.g. QR code, some kind of complex crypo method, etc).
If it is a document that allows faxing and photocopying, and nobody is taking the time to verify the authenticity of it, there are no more secure systems you can create. Things like holograms, specialist paper inlays, seals, etc can easily be faked during fax/copy. Signatures are about as good/bad as anything else.
The legal system is built on trust, verify, and punish.