In case if LR is not given by transporters, then service tax is not applicable at all because this transportation service in such a case would be covered under negative list.
As per definition u/s 65B, if there is a consignment note (i.e LR) then it would come under regime of services given by Goods Transport Agency. Now, if there is no LR, then it is normal case of service which is covered under Negative List.
Hence Service Tax is Not applicable at all.
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