The fact that GPL cases often settle does not mean the GPL is weak. In fact at least in some cases it's because the violators know they will lose and have no motivation to proceed to trial.
Also, "pro-GPL" suites play out a little differently than many people suppose. The plaintiffs are not necessarily looking for compliance but trying to collect license fees. To pick an obvious example, let's say you develop an app with Oracle MySQL using the MySQL client libraries. By linking to the MySQL libraries (for example the Connector/J JDBC driver) your application has become derivative. If you ship a binary you now either need to release all derivative code under GPL V2 or pay Oracle a commercial license fee.[1] However, if you just ship with the Oracle driver and don't release code your GPL license automatically terminates and you are now liable for the commercial license fees.
This kind of case is open-and-shut if the copyright owners get a copy of your binary with linked libraries. This is also the kind of case that should never come to trial unless the plaintiffs are really greedy or the defendants somehow don't understand their legal quandary fully. Start-ups often use GPL for this reason--it's a powerful inducement to license.
Edit: on the license fees, if you don't have a license you might owe payments going back years. The sum can run into the millions depending on the extent of violation, not to mention legal fees, disruption of having to do discovery, etc.
Also, "pro-GPL" suites play out a little differently than many people suppose. The plaintiffs are not necessarily looking for compliance but trying to collect license fees. To pick an obvious example, let's say you develop an app with Oracle MySQL using the MySQL client libraries. By linking to the MySQL libraries (for example the Connector/J JDBC driver) your application has become derivative. If you ship a binary you now either need to release all derivative code under GPL V2 or pay Oracle a commercial license fee.[1] However, if you just ship with the Oracle driver and don't release code your GPL license automatically terminates and you are now liable for the commercial license fees.
This kind of case is open-and-shut if the copyright owners get a copy of your binary with linked libraries. This is also the kind of case that should never come to trial unless the plaintiffs are really greedy or the defendants somehow don't understand their legal quandary fully. Start-ups often use GPL for this reason--it's a powerful inducement to license.
[1] https://dev.mysql.com/downloads/connector/j/5.1.html
Edit: on the license fees, if you don't have a license you might owe payments going back years. The sum can run into the millions depending on the extent of violation, not to mention legal fees, disruption of having to do discovery, etc.