We have a law which allows cops to arrest people w/o proof.

The law is not baseless. 

Sustained torture of women has necessaited this law.  The law is not sufficient enough to meet the threat No sufficient deterrance is created by this teechless lae in present form.  Women asre still tortured for dowry. Dowry is still shamelessly demanded. 

There is no law to fix the free meals availaling  guests from groom side (including near relative who are ceremonially honoured at the door of banquet hall with heavy cash and gifts) or thos e whom gifts are handed over as soon as bride enters the matrimonial house.  Attending such marriages where they know that excessive dowry is demanded.

There is no duty cast on the police to ensure and report to the court that the bride has been restored in matrimonial home inpite of  giving complaint.

There is no law to fix the priests (pandit, parson or maulana) who perform such marriages where they know that excessive dowry is demanded.

The crime is not cognisable andpolice can just take no action unless the victuim picks up courage to complaint and then too they have to refer the matter for mediation which just enahnces torture time of the victim.

There is no law to fix the neighbours (including Sarpanch/ councellor) who fail to inform the police when such torture exhists in their vicinity.

If such measures are adopted there may be shrp decline in dowry demand and toture and the law willbecome redunctant as in case of Sati Abolitin Law.

"In my opinion, every marriage should be registered with an undertaking in stamp paper by both sides that none of the parties have given or received dowry in any form or exchanged gifts from either side."

No use of such provision.  In a society when one can be paid to arrange money (over the months) to pay dowry beyond his capacity then such affidavit can also be orced from him.  Such affidavit cannot guaratee post marriae dowry related torture.

Law itself should be sodeterrent that none should pick up courage to demand dowry or agree to give dowry.

Example : Sati was abolished this way.

"they don't have to struggle or take the trouble for collecting evidences for claiming their husbands or in-laws guilty,"

In criminal matters no victim reporting any crime from petty theft to marder or terrorist is requuired to collect evidence.  Police is empowered and paid for the same by the state. Nothing special for 498a comkplainant.

No amount of laws or Police can solve social problems(evil) like dowry or moral crimes whose cause is deep rooted lack of ethics or morality in society. In order to resist evil one needs moral autonomy. Unfortunately most of the people(with some notable exceptions) of this Indian sub continent appear to lack moral autonomy and hence the lack of courage to say wrong is wrong and stop cooperating.

"The single most important quality needed to resist evil is moral autonomy. Moral autonomy is possible only through reflection, self-determination and the courage not to cooperate." Immanuel Kant (1724-1804) German philosopher

After watching the following video can anyone reflect in calmness and honestly tell who are the individuals or people who lack moral autonomy and courage to resist evil? Is it the reflection of what is morally going wrong in the rest of the Indian sub continent? What is the real evil? And what is the real reason behind lack of humanity or lack of accountability before law? Is there any shortage of laws or shortage of morality? These questions need deep reflection and courage to get honest answers https://www.youtube.com/watch?v=HAXpflv9DJg

Here is another one where Swami Satyanand Maharaj is talking about Geeta, Mahabharta etc. The talk begins for about one minute in Punjabi, but later the entire conversation is in Hindi https://www.youtube.com/watch?v=5XWaWb1rxrg The listeners of the video need to reflect and think deeply.

LAw can solve problem to great extent if the law was not teethless.  498a and DP Act  need to be more drastic.