Currently set-service doesn't have a InputObject parameter which accepts the System.ServiceProcess.ServiceController object, while other *-service cmdlets do.

Currently this doesn't work:

$a = Get-Service vds
set-service $a -startupType Automatic

while start-service and stop-service do work this way

$a = Get-Service vds
Stop-Service $a

and pipeline does also work
Get-Service vds | Set-Service -startupType Automatic

a work around is this:

$a = Get-Service vds
Set-Service $a.ServiceName -startupType Automatic