Standard contracts are in principle a good idea, but with a shared house there has to be some element of joint liability e.g. for damage to shared areas, or for gas and electricity bills. It is not reasonable to expect landlords to cover that risk; and although the airwaves are always full of stuff about 'rogue landlords' many landlords have found to their cost that some students make appalling tenants.
Some landlords bundle bills into the rent, removing the problem of being chase for unpaid bills, In my shared house two peoples names were put on the utility bills and they were responsible for collecting the money and paying it.
with regards the contracts, renting a house to a group of people and having separate contracts for each room require the building to be altered in different ways, the latter requiring each room to be self contained and lockable with fire doors on each room etc (many student houses are like this anyway) and often the landlord requires an entirely full house before letting any of the group sign contracts, often a landlord can be persuaded to let a group of 5 rent a 6 bedroom house by them volunteering to pay a higher rent to allow for the missing tenant.
Often, someone just starting renting to students will be looking at a joint everyone liable for everyone else type contract as, either the house hasn't been signed off to allow individual rooms being let, or they're a bit worried about and setting out on renting to students.
I was looking round a house once with a group of friends and promptly walked out when told that rent was to be paid by post dated cheques in advance of moving in, I asked if we would be told when the cheque was going to be cashed so I could ensure the money would be there to be told "you've got your overdraft haven't you?"
A friend of ours has just bought a house in Birmingham to rent to his son's friends figuring that the price he paid will work out similar to paying rent for both his children (rent from this funds rent for other child elsewhere), after which he'll probably sell it again, hopefully for a similar price to what he paid.