This because it is Linux or the GNU toolchains that has issues with multiple lib versions (the major source of "dependency hell"), it is the package managers.
Actually the package managers can handle it just fine (well, I know RPM can, and I *think* dpkg/apt can too); usually the problem is that the libraries are packaged in a way that doesn't support this. If two versions of a package share no files (e.g. if you provide "libxyz.so.1.0.0" in one package, and "libxyz.so.1.1.0" in another version of the same package, RPM can handle having both versions of the package installed with no problems at all. This is used, for example, to support having multiple kernel versions installed on RedHat-type systems. What becomes a problem is if you have (say) binaries in the same package, with the same name in each version, but different contents: naturally RPM will report a conflict if you try to install both.