TRIM/UNMAP does not appear to be supported for any VMware virtual disk technology. It certainly does not pass it through to the underlying host disks. The only way to reclaim unallocated space in a VMware hosted file system is to use VMware's shrinking capabilities, which tends to require defragging the file system, writing zeros to unallocated space, and then run the shrinking (many times using the vmware-vdiskmanger CLI). You have to take into account SSD wear if you are doing this process too often. 

And "modern file systems" tend to be copy-on-write, which means as they write new blocks or update old ones, they write the updated block to unallocated spaces on the disk. The original block is then either deallocated (returned to free block chain) or kept around depending on the number of other files and/or snapshots that reference the block.. That's great for SSDs but not so great for HDDs. Even though your VM may report it's using an amount of disk space, that's not what the virtual disk files consume because of not releasing previously used blocks on the host.