Many years ago (when I was young and naive), I accepted a job offer (rejecting two other offers, with some acrimony from one of them) and moved to a new country (Chile) in order to take the job, only to realize after arriving there that I did not have a work contract, just an invitation, and that I needed to enter a 4-6 month process in order to (pay to) validate my PhD diploma with a local university and get official ID papers in the new country, before the administration of the university would even consider hiring me. I was paid in the meantime (albeit the administration explained to me that my salary would be decided retroactively after being hired, and that the remaining money would be considered an advance on my research expenses, something which was quite uncomfortable to me) and eventually got hired, but the surprise and the whole process was quite uncomfortable. I did not inquire about the legality of the process at the time, assuming that since this is a state university, it had to be an example of probity and follow the law to the letter.
This was not the first time that I had found myself in such a situation. Before this job, I had received (and refused) an offer in another country (France). After announcing to me in July that I had been selected for the job, the chair of the department explained to me that I was expected to move in in August (resigning from my current position with very little anticipation, breaking up my teaching engagements for September), in order to teach in September, even though the contract was only starting in October ("for administrative reasons"). As this was a permanent position, I did not immediately refuse the offer, but asked for the contract, to which I was answered that I would normally get it after I had moved there and started to work. I did not take the job.
I now applied for another position, in another university (still Chile), and was selected. When I asked for the contract (in particular before buying a house close to the new university and moving in), I was answered that the administration was trying to make things go faster for me, but that they usually were writing and signing the contract within the three first months of employment, i.e. after I arrived and started to work (but assuring me that I would get paid for my work anyway). When I signaled that I was uncomfortable with such timing (the administration of my current university wished me to resign without delay so that they can hire someone to replace me, which I was reluctant to do without a new contract), I was asked to "trust" the university, that in their whole history they had never failed to contract someone after selecting them for a job. I was given a letter promising that I would be hired on a given date, but mentioning neither the salary nor the rank that I was offered informally by email. Two months before my starting date, I still have nothing more than an email, this letter, and some whatsapp messages to confirm that I was selected for the job. We are setting up a "vacation without salary" with my current university to allow me to start the new job while keeping the possibility to go back if anything goes wrong with the hiring process.
I trust that I will be hired and I have no reason to suspect any "evil" intentions of any person involved in such interactions. But it seems to me that such "arrangements" are in total contradiction with the very spirit and motivation behind the writing and signing of a formal contract, which would be to forfeit the need of any "trust" between two parties. Instead, I feel that those institutions view the contracts as a mere senseless administrative formality imposed on them "from above" which they have to "go around" in order to "get things done". I am (only) half thinking about telling the new university that I will NOT move to the new place until I have a contract (and teach remotely if needed while waiting for the contract). [For practical reasons, I can't rent a place and buy later.]
Hence my question (sorry for the long description of the background): How (il)legal and common is it for a university to make one move in and work BEFORE signing a contract?